Ecology. Food fight drives evolution

On page 441 of this issue, evolutionary biologists showcase the purple-throated carib hummingbird as a rare example of food supply--in this case, flower shape--spurring the evolution of a sexual dimorphism, or a feature that differs between males and females. On St. Lucia, an island in the West Indies, female caribs sport bills a third longer and twice as curved as those of their male counterparts--one of the most extreme bill differences between the sexes in any hummingbird species. In the paper, the researchers link these "whoppingly dimorphic bills" to the specific flowers the male and female caribs frequent.     

通关藤的资源调查研究

目的研究通关藤花粉活力和提高其坐果率,并为其快速繁殖提供理论依据。方法采用TTC染色法、醋酸洋红染色法、I₂-KI染色法、过氧化物酶染色法和花粉离体萌发法测定通关藤花粉活力。结果TTC染色法、醋酸洋红染色法、过氧化物酶染色法和花粉离体萌发法测得的花粉活力均低于60%,其中花粉离体萌发法测得的花粉活力最低,只有0.02%,显著低于其他4种测定方法(P<0.05)。TTC染色法、醋酸洋红染色法和过氧化物酶染色法测得的花粉活力分别为51.44%、52.10%和39.02%,三者之间差异不显著(P>0.05)。I₂-KI染色法测得的花粉活力高达90.85%,显著高于其他4种测定方法(P<0.05)。结论最适合通关藤花粉活力的测定方法为I₂-KI染色法,并且随着花龄增大花粉活力有所下降。     

Ecology and evolution of flowering plant dominance

Birds and mammals are important seed dispersers and their diversification in the Cretaceous may have created niches for many plant specialists on scattered resources. Maintaining sexual recombination through wind pollination in such sparse populations is difficult, and so angiosperms with their sophisticated systems for insect pollination were favored in many critical situations.     

Morphs,dispersal behavior,genetic similarity,and the evolution of cooperation

Genetic similarity owing to kin relationship is often invoked to explain the evolution of social cooperation. In this study, male color morphs of side-blotched lizards settle nonrandomly with respect to genetic similarity. Blue morphs tend to settle in close proximity to other blue morphs with high genetic similarity. Blue neighbors have three times the average fitness of blue males lacking such neighbors. Conversely, genetically similar males depress fitness of the orange morph. Moreover, orange males are hyperdispersed with respect to genetic similarity. Pedigree and dispersal data show that genetically similar blue neighbors are not kin. Instead, conditions for the evolution of dispersal and cooperation are promoted by an emergent property of the morph locus that increases genetic similarity within morphs: genome-wide correlational selection links many traits to the morph locus, including settlement behavior.