Relationship between population size and genetic diversity in endangered populations of the European bullhead (Cottus gobio): implications for conservation

This study investigated the relationship between the current size of endangered bullhead (Cottus gobio) populations and microsatellite genetic variability. Additionally, the microsatellite data were used to evaluate whether a genetic test for population bottlenecks was able to provide evidence of recent severe population declines. Finally, our results were used to develop conservation priorities and measures. Population size appears to be a crucial parameter in determining the amount of genetic diversity that can be preserved in bullheads, since a significant positive correlation was observed between both variables. Furthermore, in some populations we were able to detect genetic signatures of the documented decline in population size. We suggest that the most immediate goal for bullhead conservation should be to increase the size and the range of the populations, and in doing so minimise or even reverse further genetic erosion. Potential management actions like habitat quality improvement, reduction of river fragmentation and supplementation programmes (translocation, supportive breeding) are discussed.     

Catch composition and conservation management of a human-dolphin cooperative cast-net fishery in the Ayeyarwady River, Myanmar

A study of the catch composition of a cooperative fishery practiced between cast-net fishermen and Irrawaddy dolphins (Orcaella brevirostris) in the Ayeyarwady River, Myanmar, was conducted at fishing grounds near Myay Zun, Indown, The‘ Kyun and Hsithe during November and December 2006 and 2007. A total of 4139 fish from 42 species and five crustaceans from a single species were recorded in 1099 net casts made during 33 fishing sessions. Sufficient data were only available to conduct in-depth analyses of catches obtained from Myay Zun (776 net casts, 41.2% while cooperating with dolphins). These analyses indicated that catch per cast, defined by the number of fish, their weight and economic value, was higher (Mann-Whitney P < 0.001) during both 2006 (about double for all parameters) and 2007 (about triple for all parameters) while the dolphins were cooperating with fishermen. Differences in catch between cooperative and non-cooperative net casts were primarily explained by the much higher frequency of empty catches (Chi-square P < 0.001, df = 3 during both 2006 and 2007) recorded during non-cooperative casts (68.3% and 71.3% in 2006 and 2007, respectively) versus cooperative casts (13.7% and 31.6% in 2006 and 2007, respectively). Overall, fish catch could be described as meager, which may partially be explained by the abnormal timing of flow recession during both years. However, the cast-net fishermen also consistently reported dramatically depleted catches in recent years due to illegal electric fishing. Elimination of electric fishing in a recently established protected area will be crucial for conserving the dolphins and the cooperative cast-net fishery.     

Seasonal movements in the Sumatran orangutan (Pongo pygmaeus abelii) and consequences for conservation

Preservation of orangutan habitat can only be effective when their range requirements are taken into consideration. Here, the effect of the variation in fruit supply at different altitudes on the seasonal movements of orangutans is investigated. Transects were surveyed every 2 months from 1998 to 2000, at different altitudinal zones in the larger Ketambe area, Indonesia. The density of orangutan and sources of ripe fruit with soft pulp were determined along these transects. Both orangutan density and the availability of fruit varied considerably throughout the survey period at different altitudinal zones. The peaks in fruit production at different altitudes occurred in successive periods. For each altitudinal zone a significant correlation was found between orangutan density and the number of fruit sources, which shows that orangutans follow the production of fruit between these altitudinal zones within the boundaries of their home range. Orangutans with core areas in intermediate and highland areas depend seasonally on fruit production of lowland areas, and vice versa. Thus, conservation of large tracts of primary forest with a range of different altitudes is necessary to preserve the remaining orangutan population.     

Microsatellite analysis of genetic population structure of the endangered cyprinid Anaecypris hispanica in Portugal: implications for conservation

The endangered fish species Anaecypris hispanica is restricted to eight disjunct populations in the Portuguese Guadiana drainage. The genetic structure of these populations was studied in order to determine levels of genetic variation within and among populations and suggest implications for conservation of the species. Based on five microsatellite loci, the null hypothesis of population homogeneity was tested. Tests for genetic differentiation revealed highly significant differences for pairwise comparisons between all populations, and substantial overall population subdivision (F_ST=0.112). All sampled populations contained unique alleles. Our findings indicate marked genetic structuring and emphasise limited dispersal ability. The high levels of genetic diversity detected within and among A. hispanica populations suggest, however, that the observed fragmentation and reduction in population size of some populations during the last two decades, has impacted little on levels of genetic variability. Data imply that most A. hispanica populations should be managed as distinct units and that each has a high conservation value containing unique genetic variation. It is argued that geographic patterns of genetic structuring indicate the existence of eight management units.     

Island differences in population size structure and catch per unit effort and their conservation implications for Komodo dragons

Species inhabiting archipelagos are often characterised by high levels of interpopulation divergence (e.g. size related traits). This divergence may, in turn, influence their life-history. To facilitate better management and conservation of the Komodo dragon (Varanus komodoensis), an island endemic, we identified demographic differences between two island populations in Komodo National Park, Indonesia. Comparison of data collected from dragon populations inhabiting Rinca Island and the much smaller Gili Motang Island indicated that between 1994 and 2004, the Komodo dragon population on Gili Motang significantly decreased its: (1) mean body mass, (2) body condition and (3) relative abundance. These results suggest that the numerically small Gili Motang population was oscillating downwards; in contrast, the Rinca Island population had been relatively stable. More importantly these results emphasize the necessity for managers of this priority conservation species to understand further the inherent functional differences among dragon populations to develop island specific management units. Current management practices (e.g. monitoring) instigated by Komodo National Park management ignore small island dragon populations and thus run the risk of being unable to detect adverse effects for populations that are potentially most prone to decline.     

Assessing waterbird conservation objectives: An example for the Burry Inlet, UK

We use an individual-based model to assess the conservation objectives for knot Calidris canutus L. and oystercatcher Haematopus ostralegus L. on the Burry Inlet Special Protection Area (SPA), UK. Population monitoring has identified a decline in oystercatcher numbers, but cannot determine whether this is due to a decline in site quality. Long term data on cockle stocks show that the biomass of the large-sized cockles consumed by oystercatcher declined after 2004, whereas a similar decline was not observed in the smaller cockles consumed by knot. The model postdicts that during the winters of 2005/2006 to 2008/2009 the site was unable to support the number of oystercatcher present at the time it was designated (i.e. the SPA population). Large cockle biomass remained low during 2009/2010, but increases in mussel biomass meant that the model postdicted that the site could support the SPA population of oystercatcher. Knot food supplies remained high during most years, except 2008/2009 during which the model postdicted that the SPA population could not be supported. The model postdicted that the stock reserved for oystercatchers after shellfishing needed to be 2-4 times the amount consumed by the birds in order to support the bird population. We recommend that where necessary, the conservation objectives of waterbirds should be assessed using a combination of thorough population size and behaviour monitoring to identify sites with population declines, and individual-based modelling on these sites to determine whether reduction in site quality may contribute to the site-specific population decline.     

Monitoring the performance of wild-born and introduced lizards in a fragmented landscape: Implications for ex situ conservation programmes

Ex situ conservation of animal populations may benefit from captive-breeding programmes, but these are criticised because they are assumed to be difficult, time-consuming and expensive, while they do not guarantee success. However, such assumptions remain untested in most organisms; for example, introductions could be very useful for recovering populations of small-sized species with short generation time, no learned behaviours, and ease to rear in captivity. Here, we document an easy, cheap and successful reintroduction programme of the lacertid lizard Psammodromus algirus. Two captive-bred cohorts (178 juveniles in 2001 and 187 in 2002) were released in four woodland fragments (0.9-5.2 ha) at two localities (B and V); B housed a stable lizard population whereas V apparently lacked a viable population of lizards. We monitored introduced and native lizards during 2002 and 2003, and carried out a corroborative searching in 2006 which confirmed the existence of a lizard population at site V. Introduced lizards had higher activity and dispersed more frequently among woodland fragments than native ones. Survivorship and growth rates were similar for both groups, but introduced juveniles were about 25% larger than native ones, due to both early hatching and better rearing conditions. The whole procedure was easily implemented in our Faculty facilities (mean hatching and hatchling survival rates of 0.90 and 0.87), and cost less than 20,000 € (excluding salaries). Therefore, similar programmes may be of wide application in small animals and of practical importance for species with a meta-population structure living in fragmented landscapes.     

Factors influencing survival and long-term population viability of New Zealand long-tailed bats (Chalinolobus tuberculatus): Implications for conservation

A population viability analysis is important for the management of endangered populations and requires the estimation of survival parameters. The long-tailed bat (Chalinolobus tuberculatus) is one of only two native terrestrial mammals currently found in New Zealand and is classed as vulnerable. Its viability in temperate beech (Nothofagus) forest, Eglinton Valley, Fiordland, New Zealand was estimated using mark-recapture data collected between 1993 and 2003 using the Program MARK. Survival was estimated based on a total of 5286 captures representing 1026 individuals. Overall annual survival varied between 0.34 and 0.83 but varied significantly among three sub-populations and with sex and age. Females generally had a higher survival rate compared to males; and adults had higher survival relative to juveniles. Survival of all bats was lower in years when the number of introduced mammalian predators was high and when the winter temperature was warmer than average. High numbers of introduced predators occurred during three of the 10 years in the study. Climate change may mean that the conditions that promote high predator numbers may occur more frequently. A preliminary population viability analysis using a projection matrix on the overall adult female population showed an average 5% decline per year (λ = 0.95). Increased predator control targeting a range of predators is required in years when their numbers are high in order to halt the decline of this population of long-tailed bats. Population estimates using minimum number alive estimates supported the population estimates derived from Program MARK and a population viability analysis using matrices.     

Artificial dispersal of endangered epiphytic lichens: a tool for conservation in boreal forest landscapes

Due to increasing fragmentation of the boreal forests of Fennoscandia, a number of epiphytic lichens are now becoming threatened. Since these species typically are limited by a poor ability of dispersal, one possible but largely unexplored strategy for conservation is to disperse lichen material artificially into suitable habitats. Therefore, the objective of this study was to evaluate survival and vitality in lichen fragments from Evernia divaricata (L.) Ach. and Ramalina dilacerata (Hoffm.) Hoffm. after transplantation into three different stand types situated in northern Sweden, using different fragment sizes and modes of transplantation. After one year, survival ranged between 85% and 97.5%, and new growth occurred at all transplantation sites. The study has shown that transplantations of small fragments might constitute a resource-efficient option for establishment of new populations of endangered lichen species, or for enlarging their populations at the present sites of occurrence. In addition, the mode of transplantation was of importance for fragment vitality.     

AFLP fingerprinting of Anchusa (Boraginaceae) in the Corso-Sardinian system: Genetic diversity, population differentiation and conservation priorities in an insular endemic group threatened with extinction

Although several plants endemic to Corsica and Sardinia are included in various redlists, no attempts have been made to analyse their genetic diversity with molecular techniques. Genus Anchusa occurs with seven taxa in either mountain or coastal habitats of the two islands, but the very restricted range and low population size pose these endemisms in a very precarious conservation status. Highly variable markers (AFLP) were therefore used to analyse the patterns and levels of genetic diversity in a sample of 11 populations from the entire range of the group.Results indicate the separation between a mountain genic pool including Anchusa formosa, Anchusa capellii and Anchusa montelinasana, and four groups of coastal accessions. In spite of small size, mountain taxa show low interpopulation differentiation (F_st = 0.02) and relatively high intrapopulation genetic variation (0.365), while coastal accessions showed on average a stronger differentiation (mean F_st = 0.20) and a lower diversity (0.281), possibly due to higher rates of inbreeding. The particularly low levels of variation found in A. sardoa, A. littorea and A. crispa ssp. maritima from the Coghinas bay are likely due to a historical decrease of populations and to bottleneck events caused by loss of habitat and natural stochastic factors on sand dune ecosystems. While habitat maintenance and regulation of grazing by domestic herbivores should be sufficient to ensure the persistence of the mountain endemics, additional actions of in situ and ex situ conservation are needed for the critically endangered coastal species A. sardoa and A. littorea. A. crispa showed a relatively high variation, especially on Corsica. No correlation between population size and genetic variation was found in the latter species, highlighting the importance of the small patches for its conservation. Also, the genetic separation between subspecies crispa and maritima stresses the need of keeping them distinct in redlists and conservation actions on Sardinia.     

Population genetic structure and the conservation of isolated populations of Acacia raddiana in the Negev Desert

There is much concern over the high mortality of many populations of Acacia raddiana, a keystone tree species in the Negev desert of Israel. We used random amplified polymorphic DNA (RAPD) to assess patterns of genetic variation within and among 12 populations of A. raddiana from the Arava (Syrian-African Rift) valley and western Negev. A high level of genetic polymorphism was recorded within populations. An analysis of molecular variance (AMOVA) showed that about 59.4% of total genetic variance occurred among populations, which is considerably greater population differentiation than that recorded for other outbreeding species. Cluster and principal coordinates analyses and AMOVA indicate that the western Negev and Arava valley populations are highly differentiated. We suggest that there may have been two invasions of A. raddiana into Israel: one across the northern Sinai/Gaza Strip area into the western Negev, with some plants reaching the Dead Sea and a second invasion across the southern part of the Sinai peninsula, or even from Saudi Arabia, up to the Arava valley. From the conservation point of view, each population should be conserved separately because they are genetically highly differentiated and loss of any one population would lead to a dramatic loss of genetic variation. The mixing of genetically distinct populations may give rise to outbreeding depression (particularly because of GXE interactions). An obvious first step to the maintenance of this species' genetic diversity is the separate management of the western Negev and Arava valley populations because of their different evolutionary histories.     

Site fidelity and along-shore range in Hector's dolphin, an endangered marine dolphin from New Zealand

To document site fidelity and the alongshore range of individual Hector's dolphins we analysed sightings of 32 photographically identified dolphins, each seen ?10 times at Banks Peninsula, New Zealand, between 1985 and 1997. The furthest two sightings of an individual were 106 km apart. All other individuals ranged over less than 60 km (x?=31.0 km, SE=2.43) of coastline. Gender did not significantly influence alongshore range (female x?=30.4 km, SE =3.21, n=18; male x?=27.4 km, SE=5.68, n=5). Site fidelity was high: for example, on average, individuals were seen in Akaroa Harbour for about two thirds of the years they were known to be alive. These data suggest that impacts on Hector's dolphins are most appropriately managed on a small spatial scale.     

Reproductive biology and conservation implications of three endangered snapdragon species (Antirrhinum, Plantaginaceae)

About 32% of Antirrhinum species are considered to be endangered; however, no field studies have focused on their reproductive biology. In this work, several aspects of the reproductive biology (flowering phenology, floral biology, breeding system) and potential limits on seed quantity and quality (pollen limitation, inbreeding depression) were studied in natural populations of three endangered species of the genus (Antirrhinum charidemi, Antirrhinum subbaeticum, Antirrhinum valentinum). Results disclose that all three species need insect visitors for seed production since fruit set after autonomous self-pollination was lower than under hand cross-pollination. A. charidemi and A. valentinum were mainly self-incompatible, whereas A. subbaeticum was self-compatible but herkogamous. Supplementary pollination in open-pollinated flowers only increased fruit set and seed set relative to controls in a given population of A. valentinum. Preliminary data on inbreeding depression at early life-cycle stages of the self-compatible A. subbaeticum revealed that the cumulative level was low. Despite the three species being closely related and sharing many ecological characteristics, they show different mating systems, and different factors limit seed quantity and quality. Thus, caution should be taken when making a common conservation plan for a group of closely related taxa.     

Population decline of Macaca sylvanus in the middle atlas of Morocco

An eight-year-long census and habitat evaluation of the Macaca sylvanus population was conducted in a 484-km² area of the central region of the Middle Atlas Mountains in Morocco between June 1994 and October 2002. The authors walked a 93.5-km circuit - divided into 16 transect segments - 30 times with teams of trained research assistant volunteers, collecting data on a total of 2,805 linear km. Previous studies had reported an average density of 44-70 individuals per km², while data from the present study indicate a progressive population decline, from 25 to 30 individuals per km², down to a current average density of 7-10 I/km². The population decline is attributed to the loss of prime habitat, mainly cedar forest, which has significantly decreased from 1994 to 2002, due to the growing impact of overgrazing by mixed flocks of goats and sheep and consequent forest degradation. At present, human-caused habitat deterioration in the Middle Atlas risks further compromising the future of the world’s only remaining large M. sylvanus population.     

Distribution, status, and conservation needs of Asian elephants (Elephas maximus) in Lampung Province, Sumatra, Indonesia

In the mid 1980s, Asian elephant (Elephas maximus) populations were believed to persist in 44 populations on the Indonesian island of Sumatra. Twelve of these populations occurred in Lampung Province, but our surveys revealed that only three were extant in 2002. Causal factors underlying this decline include human population growth, changes in land use, and human-elephant conflict. Nevertheless, our surveys in the Province’s two national parks, Bukit Barisan Selatan and Way Kambas, produced population estimates of 498 (95% CI = [373, 666]) and 180 (95% CI = [144, 225]) elephants, respectively. The estimate for Bukit Barisan Selatan is much larger than previous estimates; the estimate for Way Kambas falls between previous estimates. The third population was much smaller and may not be viable. These are the first estimates for Southeast Asian elephant populations based on rigorous sampling-based methods that satisfied the assumptions of the models used, and they suggest that elephant numbers in these parks are of international importance. While our results suggest that Sumatra’s remaining elephant populations may be larger than expected, they also suggest that the future for these animals is bleak. Human-elephant conflict was reported around all three areas in Lampung and their elephant populations are currently threatened by habitat loss and poaching. Local solutions are possible, but will require much greater commitment by all stakeholders.     

Genetic structure, population dynamics, and conservation of Black caiman (Melanosuchus niger)

Microsatellite DNA polymorphisms were screened in seven populations of the largest Neotropical predator, the Black caiman Melanosuchus niger (n = 169), originating from Brazil, French Guiana and Ecuador. Eight loci were used, for a total of 62 alleles. The Ecuadorian population had the lowest number of alleles, heterozygosity and gene diversity; populations of the Guianas region exhibited intermediate diversities; highest values were recorded in the two populations of the Amazon and Rio Negro. During the last century Melanosuchus populations have been reduced to 1-10% of their initial levels because of hunting pressure, but no strong loss of genetic diversity was observed. Both the inter-locus g-test and the Pk distribution suggested no recent important recovery and/or expansion of current populations. On a global scale, the inter-population variation of alleles indicated strong differentiation (F_ST = 0.137).Populations were significantly isolated from each other, with rather limited gene flow; however, these gene flow levels are sufficiently high for recolonization processes to effectively act at regional scales. In French Guiana, genetic structuring is observed between populations of two geographically close but ecologically distinct habitats, an estuary and a swamp. Similar divergence is observed in Brazil between geographically proximate “black water” and “white water” populations. As a consequence, the conservation strategy of the Black caiman should include adequate ecosystem management, with strong attention to preservation of habitat integrity. Distribution of genetic diversity suggests that current populations originated from the central Amazonian region. Dispersal of the species may thus have been deeply influenced by major climatic changes during the Holocene/Pleistocene period, when the Amazonian hydrographic networks were altered. Major ecological changes such as glaciations, marine transgressions and a hypothesized presence of an Amazonian Lake could have resulted in extension of Black caiman habitats followed by isolation.     

Comparative water snake ecology: conservation of mobile animals that use temporally dynamic resources

Obtaining information on movement and spatial patterns of animals and understanding the factors that shape their movements about the landscape are critical steps in designing conservation strategies. We conducted a comparative radiotelemetry study of two snake species, the northern water snake, Nerodia sipedon sipedon, and the imperiled copperbelly water snake, Nerodia erythrogaster neglecta, in northwest Ohio and southern Michigan to assess differences in movement patterns, spatial ecology, and resource use. N. e. neglecta moved distances (53.3 ± 7.1 m/day and 4809 ± 603 m/year) over twice as far as N. s. sipedon (25.6 ± 2.7 m/day and 2244 ± 228 m/year), and used areas nearly four times larger (15.8 ± 2.7 ha) than N. s. sipedon (4.0 ± 0.9 ha). When wetlands were widely dispersed in the landscape, N. e. neglecta moved longer distances and used larger areas, whereas spatial and movement patterns in N. s. sipedon were unaffected by wetland spatial distribution. N. e. neglecta’s long movements and large area use are likely related to its use of variable resources such as ephemeral wetlands and anuran prey. N. s. sipedon used more permanent wetlands and preyed more generally on fish and anurans. Habitat alterations that change the spatial distribution of wetlands in the landscape, such as the loss of small isolated wetlands, have likely increased energetic costs and mortality rates for N. e. neglecta. Conservation strategies for vagile wetland animals that use spatially and temporally variable resources over broad spatial scales should focus on protecting and restoring large areas with numerous, heterogeneous wetlands.     

Ecology of the native and introduced crayfishes Austropotamobius pallipes and Procambarus clarkii in southern Spain and implications for conservation of the native species

The former and present distribution of white clawed crayfish (Austropotamobius pallipes) in the province of Granada (southern Spain) is studied. Before 1980 it was widely distributed but at present only 16 populations exist. The decline is related to the presence of the freshwater red-swamp crayfish (Procambarus clarkii), an American species, vector of the aphanomycosis disease, introduced to the Iberian Peninsula in 1974 and now widely distributed in the watercourses and marshes of southern Spain. To establish an appropriate conservation policy for A. pallipes at its southernmost distribution limit, we studied watercourses from two river basins, Genil and Guadiana Menor, (tributaries of the Guadalquivir River). P. clarkii inhabits the medium to lower reaches of these two river basins (with its upper limit at 820 m a.s.l.). The distribution of this species was best explained by the effect of three of the 12 analyzed variables: altitude, water-current and minimum winter temperatures. From our results, the repopulation of the native crayfish is almost impossible in those reaches inhabited by P. clarkii. However, based on the habitat selection study, it is clear that upper reaches are unsuitable for the red-swamp crayfish, where the native white-clawed crayfish may have greater survival possibilities, and these sites can be used for future restocking projects.     

Higher breeding densities of the threatened little bustard Tetrax tetrax occur in larger grassland fields: Implications for conservation

Previous studies have found that densities of little bustard Tetrax tetrax breeding males tend to be higher in areas with smaller agricultural fields, presumably due to increased habitat diversity. However, exceptionally high densities have been found in large grassland fields in Portugal, which suggests that the influence of field size varies geographically, and that the role of this factor is not yet fully understood, despite its importance as a key management issue.We studied how field size, together with vegetation structure, influences the presence and density of breeding little bustards in a region of southern Portugal. Fifty-four grassland fields were sampled in 2007 and another 29 in 2008, with sizes ranging from 23 to 172 ha. A total of 183 breeding males were found in 47 of these fields, reaching densities of up to 37 males/100 ha. A higher probability of occurrence of breeding males was found in larger fields with a vegetation height below 40 cm and field size alone explained 46% of the variability in male density. These results suggest that larger continuous areas of suitable habitat attract many males, most likely as a consequence of their lek mating system. We conclude that conservation efforts, in a landscape context of large farm sizes, should: (1) be channelled to farms with large fields; (2) ensure adequate livestock grazing to create suitable habitat and (3) promote management at a landscape level to ensure the most continuous grassland habitat patches possible.