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History Events (history + event)
Selected AbstractsTHE HISTORICAL BIOGEOGRAPHY OF TWO CARIBBEAN BUTTERFLIES (LEPIDOPTERA: HELICONIIDAE) AS INFERRED FROM GENETIC VARIATION AT MULTIPLE LOCIEVOLUTION, Issue 3 2002Neil Davies Abstract Mitochondrial DNA and allozyme variation was examined in populations of two Neotropical butterflies, Heliconius charithonia and Dryas iulia. On the mainland, both species showed evidence of considerable gene flow over huge distances. The island populations, however, revealed significant genetic divergence across some, but not all, ocean passages. Despite the phylogenetic relatedness and broadly similar ecologies of these two butterflies, their intraspecific biogeography clearly differed. Phylogenetic analyses of mitochondrial DNA sequences revealed that populations of D. iulia north of St. Vincent are monophyletic and were probably derived from South America. By contrast, the Jamaican subspecies of H. charithonia rendered West Indian H. charithonia polyphyletic with respect to the mainland populations; thus, H. charithonia seems to have colonized the Greater Antilles on at least two separate occasions from Central America. Colonization velocity does not correlate with subsequent levels of gene flow in either species. Even where range expansion seems to have been instantaneous on a geological timescale, significant allele frequency differences at allozyme loci demonstrate that gene flow is severely curtailed across narrow ocean passages. Stochastic extinction, rapid (re)colonization, but low gene flow probably explain why, in the same species, some islands support genetically distinct and nonexpanding populations, while nearby a single lineage is distributed across several islands. Despite the differences, some common biogeographic patterns were evident between these butterflies and other West Indian taxa; such congruence suggests that intraspecific evolution in the West Indies has been somewhat constrained by earth history events, such as changes in sea level. [source] The genetic basis of early-life morphological traits and their relation to alternative male reproductive tactics in Atlantic salmonJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2010D. J. PáEZ Abstract Although heritability estimates for traits potentially under natural selection are increasingly being reported, their estimation remains a challenge if we are to understand the patterns of adaptive phenotypic change in nature. Given the potentially important role of selection on the early life phenotype, and thereby on future life history events in many fish species, we conducted a common garden experiment, using the Atlantic salmon (Salmo salar L.), with two major aims. The first objective is to determine how the site of origin, the paternal sexual tactic and additive genetic effects influence phenotypic variation of several morphological traits at hatching and emergence. The second aim is to test whether a link exists between phenotypic characteristics early in life and the incidence of male alternative tactics later in life. We found no evidence of a site or paternal effect on any morphological trait at hatching or emergence, suggesting that the spatial phenotypic differences observed in the natural river system from which these fish originated are mainly environmentally driven. However, we do find significant heritabilities and maternal effects for several traits, including body size. No direct evidence was found correlating the incidence of precocious maturation with early life characteristics. We suggest that under good growing conditions, body size and other traits at early developmental stages are not reliable cues for the surpassing of the threshold values associated with male sexual development. [source] Biogeography of the livebearing fish Poecilia gillii in Costa Rica: are phylogeographical breaks congruent with fish community boundaries?MOLECULAR ECOLOGY, Issue 19 2009JARED B. LEE Abstract One of the original goals of phylogeography was to use genetic data to identify historical events that might contribute to breaks among communities. In this study, we examine the phylogeography of a common livebearing fish (Poecilia gillii) from Costa Rica. Our goal was to determine if phylogeographical breaks in this species were congruent with previously defined boundaries among four fish community provinces. We hypothesized that if abiotic factors influence both community boundaries and genetic structuring in P. gillii then we might find four clades within our focal species that were geographically separated along community boundary lines. Similarly, we expected to find most of the genetic variation in P. gillii partitioned among these four geographical regions. We generated DNA sequence data (mitochondrial cytochrome b and nuclear S7 small ribosomal subunit) for 260 individuals from 42 populations distributed across Costa Rica. We analysed these data using phylogenetic (parsimony and likelihood) and coalescent approaches to estimate phylogenetic relationships among haplotypes, patterns of gene flow and effective population size. Contrary to our expectations, we did not find four monophyletic groups that mapped cleanly to our geographical community provinces. However, one of our clades was restricted to a single province, suggesting that common earth history events could be responsible for both genetic structuring in P. gillii and fish community composition in this area. However, our results show a complex pattern of gene flow throughout other regions in Costa Rica where genetic structuring is not predicted by community province boundaries. [source] Simulation of the population dynamics and social structure of the Virunga mountain gorillasAMERICAN JOURNAL OF PRIMATOLOGY, Issue 4 2004Martha M. Robbins Abstract An agent-based model was developed to simulate the growth rate, age structure, and social system of the endangered mountain gorillas (Gorilla beringei beringei) in the Virunga Volcanoes region. The model was used to compare two types of data: 1) estimates of the overall population size, age structure, and social structure, as measured by six censuses of the entire region that were conducted in 1971,2000; and 2) information about birth rates, mortality rates, dispersal patterns, and other life history events, as measured from three to five habituated research groups since 1967. On the basis of the research-group data, the "base simulation" predicted a higher growth rate than that observed from the census data (3% vs. 1%). This was as expected, because the research groups have indeed grown faster than the overall population. Additional simulations suggested that the research groups primarily have a lower mortality rate, rather than higher birth rates, compared to the overall population. Predictions from the base simulation generally fell within the range of census values for the average group size, the percentage of multimale groups, and the distribution of females among groups. However, other discrepancies predicted from the research-group data were a higher percentage of adult males than observed, an overestimation of the number of multimale groups with more than two silverbacks, and an overestimated number of groups with only two or three members. Possible causes for such discrepancies include inaccuracies in the census techniques used, and/or limitations with the long-term demographic data set obtained from only a few research groups of a long-lived species. In particular, estimates of mortality and male dispersal obtained from the research groups may not be representative of the entire population. Our final simulation addressed these discrepancies, and provided a better basis for further studies on the complex relationships among individual life history events, group composition, population age structure, and growth rate patterns. Am. J. Primatol. 63:201,223, 2004. © 2004 Wiley-Liss, Inc. [source] Impact of ocean barriers, topography, and glaciation on the phylogeography of the catfish Trichomycterus areolatus (Teleostei: Trichomycteridae) in ChileBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2009PETER J. UNMACK We examined the role of several earth history events on the phylogeographic distribution of the catfish Trichomycterus areolatus in Chile using the cytochrome b gene. We explored three biogeographic hypotheses: that sea level changes have resulted in the isolation of populations by drainages; that glaciation has impacted genetic diversity; and that ichthyological subprovince boundaries correspond to phylogeographic breaks in our focal species. We found seven well-supported clades within T. areolatus with high levels of genetic divergence. The strongest signal in our data was for an important role of sea level changes structuring populations. Five of the seven clades mapped cleanly to the geographic landscape and breaks corresponded closely to areas of narrowest continental shelf. In addition, few haplotypes were shared between rivers within clades, suggesting that only limited local movement of individuals has occurred. There was no relationship between the levels of genetic diversity and the proportion of individual drainages covered by glaciers during the last glacial maximum. Two phylogeographic breaks within T. areolatus did match the two previously identified faunal boundaries, but we found three additional breaks, which suggests that faunal breaks have only limited utility in explaining phylogeographic patterns. These results imply that the narrow continental shelf coupled with sea level changes had a strong influence on the obligate freshwater fishes in Chile. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 876,892. [source] | ||||||||||