PHYLOGENETIC ANALYSIS OF THE EVOLUTION OF ALTERNATIVE SOCIAL BEHAVIOR IN THE MANAKINS (AVES: PIPRIDAE)

Phylogenetic analyses of lekking, lek spatial organization, and cooperative and coordinated lek display in the manakins (Aves: Pipridae) demonstrate that variation in social behavior in the group has a strong, phylogenetic component. Two of the three classes of social behavior examined also show significant phylogenetic constraints. Current adaptive plasticity models are insufficient to explain the phylogenetic variation in these behaviors in the manakins. These findings support the conclusion that vertebrate reproductive social behavior has an evolutionary history, and that it is not determined solely by adaptive individual plasticity to current conditions. The evolution of social behavior, particularly through sexual selection, can have historical consequences that can limit subsequent behavioral adaptation.     

Genetic structure in a tropical lek-breeding bird, the blue manakin (Chiroxiphia caudata) in the Brazilian Atlantic Forest

Determining the genetic structure of tropical bird populations is important for assessing potential genetic effects of future habitat fragmentation and for testing hypotheses about evolutionary mechanisms promoting diversification. Here we used 10 microsatellite DNA loci to describe levels of genetic differentiation for five populations of the lek-mating blue manakin (Chiroxiphia caudata), sampled along a 414-km transect within the largest remaining continuous tract of the highly endangered Atlantic Forest habitat in southeast Brazil. We found small but significant levels of differentiation between most populations. F(ST) values varied from 0.0 to 0.023 (overall F(ST)=0.012) that conformed to a strong isolation by distance relationship, suggesting that observed levels of differentiation are a result of migration-drift equilibrium. N(e)m values estimated using a coalescent-based method were small (相似文献   

Isolation and characterization of microsatellite loci in the blue manakin,Chiroxiphia caudata (Aves,Pipridae)

We designed primers for amplifying 11 polymorphic microsatellite loci in the blue manakin, Chiroxiphia caudata, a neotropical passerine bird which inhabits a critically endangered tropical ecosystem, the Brazilian Atlantic forest. Based on genotypes from 24 individuals from a single population, we detected between four and 22 alleles per locus with observed heterozygosities ranging from 0.54 to 0.92. These highly variable loci will be useful for determining levels of population differentiation and assessing the impact of habitat fragmentation on levels of genetic variation in isolated populations of these birds.     

Isolation and characterization of microsatellite markers from the white-ruffed manakin Corapipo altera (Aves, Pipridae)

We describe 15 polymorphic microsatellite loci from the white-ruffed manakin Corapipo altera, a common understory bird of Neotropical lowland and montane evergreen forests from eastern Honduras to northwestern Colombia. These markers were developed in order to assess population structure and genetic diversity in a fragmented landscape, and to study gene flow between forest fragments. Primers were tested on a population of 159 individuals from the Coto Brus region of southwestern Costa Rica. We found between four and 23 alleles per locus, and observed heterozygosities ranging from 0.23 to 0.93.     

Demographic consequences of sexual selection in the long-tailed manakin

Demographic divergence between the sexes is a major consequenceof sexual selection. Matrix-based demographic measures, includingthe sensitivity and elasticity of (population growth rate,fitness) to survival and fertility rates are powerful indexesof intersexual divergence. Many morphological, behavioral, andecological differences distinguish males and females in lekkinglong-tailed manakins (Chiroxiphia linearis), and none is moredramatic than the demographic divergence. Only 16 of 142 (8%)banded males copulated during an 8-year period. The mean estimatedage of male copulators was 10.1 years (SD = 2.2), and only 5of 166 copulations were by males 8 years old. Females probablybegin reproduction at age 1 or 2. The reproductive value curvereached a peak of 15.0 for 12th-year males, versus 2.7 for sixth-yearfemales. The matrix-based elasticity of X to survival rateswas greater in males (91% of total elasticity) than in females(80% of total). In a literature-based, interspecific comparison,the difference in elasticity to survival between the male andfemale manakins (91–80=11; ranks 2 and 9 of 16 species/sexcombinations) was greater than that between the sexes in northernelephant seals (90–84=6; ranks 3 and 8), which have thehighest variance of male mating success documented for mammals;red deer (88–87=1; ranks 4 and 5); Galapagos cactus finches(79–74=5; ranks 10 and 12); and acorn woodpeckers (76–74=2;ranks 11 and 13). In the face of continuing debate over appropriatemeasures of sexual selection, matrix-based demographic techniquesfacilitate quantitative, comparative analyses of the life-historyconsequences of sexual selection. Measures of intersexual demographicdivergence may provide insights into heretofore puzzling instancesof sexual selection in species with little dimorphism in sizeor ornament.     

Social networks in the lek-mating wire-tailed manakin (Pipra filicauda)

How social structure interacts with individual behaviour and fitness remains understudied despite its potential importance to the evolution of cooperation. Recent applications of network theory to social behaviour advance our understanding of the role of social interactions in various contexts. Here we applied network theory to the social system of lek-mating wire-tailed manakins (Pipra filicauda, Pipridae, Aves). We analysed the network of interactions among males in order to begin building a comparative framework to understand where coordinated display behaviour lies along the continuum from solitary to obligately cooperative dual-male displays in the family Pipridae. Network degree (the number of links from a male to others) ranged from 1 to 10, with low mean and high variance, consistent with the theory for the evolution of cooperation within social networks. We also assessed factors that could predict social and reproductive success of males. Four network metrics, degree, eigenvector centrality, information centrality and reach, some of which assess circuitous as well as the shortest (geodesic) paths of male connectivity, predicted male social rise. The duration of a male's territorial tenure during the 4 years of the study predicted his probability of siring offspring.     

The development of coordinated singing in cooperatively displaying long-tailed manakins

Long-tailed manakins (Chiroxiphia linearis) have a puzzlingsocial system in which teams of two males display cooperativelyin dispersed lek arenas, but only the alpha partner mates withvisiting females. One benefit of performing as a nonmatingpartner might be to gain experience as an "apprentice" to improvethe performance of the complex duet song and joint dance. Weexamined the relationship between the age of singers and twomeasures of singing performance: song variability and soundfrequency matching. Singing performance improved with age;variability in four song characteristics of males less than3 years old was greater than that in their older partners,and frequency matching increased with the age of the younger partner. Randomization tests of song samples from seven well-establishedteams showed that males did not track the song-to-song variationin their partners' singing. Another randomization test showedthat frequency matching by these teams was higher than thatof randomly paired partners. We considered three alternativehypotheses for the congruent songs: (1) short-term accommodation to the partner's song; (2) active choice of partners with similarintrinsic frequencies; and (3) long-term development of congruentsong through either practice or song copying. Our results andevidence from long-term monitoring of banded birds best supportthe hypothesis that frequency matching develops over severalyears during the complex and protracted process of partner formation. Nonmating males may benefit from increasing theircompetence at display, eventually enjoying increased matingsuccess when they inherit display sites from older males.     

Intersexual spatial relationships in a lekking species: blue-crowned manakins and female hot spots

Leks offer an intriguing evolutionary problem: why do malesaggregate when this apparently leads to fitness costs? Aggregationcosts can be balanced if males settle on patches where theyare more likely to encounter females (hot-spot hypothesis).We evaluated whether female hot spots can account for patternsof lek structure in the blue-crowned manakin (Lepidothrix coronata)by modeling female distribution patterns relative to lek locationsin two 100-ha plots. Individual females were mapped based onnest locations and capture points and had their home ranges(HRs) modeled based on radiotelemetry data. The number of femalesthat lekking males can be expected to encounter was estimatedas the number of individual female HRs overlapping each maleterritory; hot spots were defined as patches where more femalesare found than average. We investigated how changes in femaleHR size and devaluation effects (decrease in female availabilitydue to the presence of neighboring males) influence male accessto females. Both factors strongly influenced the expected ratesof female encounter, but the hot-spot hypothesis was not supported:most male territories consistently overlapped fewer or justas many female HRs as expected by chance. Leks were not closerto hot spots than similar-sized nonlek sites. A proportion ofmales were, indeed, settled at hot spots, but, contrary to predictionsof the hot-spot hypothesis, they belonged to smaller leks thanmales located outside hot spots. Our results indicate that thislack of spatial correlation between males and females resultspartly from differences in sex-specific habitat preferences.     

Effects of forest fragmentation on the lekking behavior of White-throated Manakins in Central Amazonia

Forest fragmentation can affect various aspects of population dynamics, but few investigators have assessed possible effects on the behavior of a species. Loss of habitat may limit population recruitment and abundance, which may alter breeding dynamics in forest remnants. We examined the lekking behavior of White-throated Manakins (Corapipo gutturalis) in a fragmented landscape to determine if forest fragmentation affected the spatial distribution of display courts and male behavior at courts. We captured and observed males at 19 courts located in 11 primary forests of different sizes in forest habitats of the Biological Dynamics of Forest Fragments Project area, an experimentally fragmented landscape located in the central Brazilian Amazon, and estimated their spatial distribution as the distance to the nearest court in the landscape. We quantified habitat loss using the proportion of forest cover surrounding courts and their distances to forest edges. No courts were detected in 1-ha forest fragments, suggesting direct effects from habitat loss following fragmentation that affected connectivity and thus recruitment and persistence of courts in the smallest fragments. The spatial distribution of display courts in forests larger than 10 ha remained unaltered, compared to display courts in continuous forests, but adult males were less numerous on courts with a higher percentage of forest cover and they displayed less on courts closer to forest edges. The spatial distribution of courts also contributed to variation in male social behavior, with more juvenile males present and adult males displaying at lower rates at more isolated courts. Although White-throated Manakins are locally common, the observed behavioral changes in response to habitat loss may affect their population dynamics. Our results show the importance of assessing behavioral changes in conservation programs and, in particular, of including biologically relevant measures of habitat loss in addressing its possible effects on species persistence in fragmented landscapes.