The Neolithic Transition And The Genetics Of Populations In Europe: A Review

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137425/1/evo00491.pd

Correlated Morphological and Genetic Patterns in Embothrium coccineum (Proteaceae) Across Climate and Geography: Can Embothrium Survive Patagonian Climate Change?

Adaptive radiation and reproductive isolation can determine the biogeographic structure of any species. We examine patterns of biotic variation in Embothrium coccineum, a Proteaceae tree that spans 20º of latitude and is both morphologically and genetically highly variable. We aim to: (1) explore the correspondence between these biotic patterns and current geographic and climatic gradients, and (2) determine whether and how those patterns are likely to respond to changing climate. We conducted separate Principal Components Analysis on biotic and abiotic sets of variables for 34 populations of Embothrium coccineum, accounting for a large fraction of the total variation in each. We then used canonical correlation analyses to optimize the match of those gradients onto each other. Smaller, rounder leaves and particular alleles typify the colder-drier parts of the range, while larger, lanceolate leaves and other alleles typify warmer-moister areas. Finally we mapped biotic profiles onto a predicted climatic landscape, based on doubling of CO2 projections. The climatic regime is predicted to shift geographically, but this lineage has successfully responded to repeated and dramatic climatic shifts since the Oligocene, and it should also be able to move and adapt quickly enough to meet the present challenge. More generally, our analytic approach can be extended to analysis of biotic and abiotic patterns in other species facing climatic challenges. Where there is enough biogeographic variation to provide adaptively relevant substrate, and where propagule dispersal is sufficiently extensive to keep up with the pace of spatial climatic shift, such taxa should be able to cope with shifting climate.Fil: Souto, Cintia Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio de Ecotono; ArgentinaFil: Smouse, Peter E.. Rutgers University. Department of Ecology, Evolution and Natural Resources; Estados Unido

Mathematical models for continuous culture growth dynamics of mixed populations subsisting on a heterogeneous resource base. II. Predation and trophic structure

Models are presented for the joint dynamics of predators and prey, maintained in continuous flow chemostat culture. The predators are visualized as subsisting on one or more prey organisms, which in turn are visualized as subsisting on one or more substrate resources supplied by the investigator. The dynamic equations are translated into an analogous Lotka-Volterra predation model, and the criteria for the existence and stability of various equilibria are indicated. Denoting the number of different predator organisms as NH, the number of different prey organisms by NI and the number of different substrates as NJ, it is shown that the joint coexistence of all components requires 0 [les] NI - NH [les] NJ. The model is extended to more complex situations by including additional trophic layers and by allowing trophic layer "leap-frogging." The model may always be translated into an approximately quadratic differential equation of the Lotka-Volterra type. The [alpha]- and [beta]-coefficients of these latter are really variables, and become quite complex for some of the multi-layered models.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24239/1/0000502.pd

A heterogeneity test for fine-scale genetic structure

For organisms with limited vagility and/or occupying patchy habitats, we often encounter nonrandom patterns of genetic affinity over relatively small spatial scales, labelled fine-scale genetic structure. Both the extent and decay rate of that pattern can be expected to depend on numerous interesting demographic, ecological, historical, and mating system factors, and it would be useful to be able to compare different situations. There is, however, no heterogeneity test currently available for fine-scale genetic structure that would provide us with any guidance on whether the differences we encounter are statistically credible. Here, we develop a general nonparametric heterogeneity test, elaborating on standard autocorrelation methods for pairs of individuals. We first develop a 'pooled within-population' correlogram, where the distance classes (lags) can be defined as functions of distance. Using that pooled correlogram as our null-hypothesis reference frame, we then develop a heterogeneity test of the autocorrelations among different populations, lag-by-lag. From these single-lag tests, we construct an analogous test of heterogeneity for multilag correlograms. We illustrate with a pair of biological examples, one involving the Australian bush rat, the other involving toadshade trillium. The Australian bush rat has limited vagility, and sometimes occupies patchy habitat. We show that the autocorrelation pattern diverges somewhat between continuous and patchy habitat types. For toadshade trillium, clonal replication in Piedmont populations substantially increases autocorrelation for short lags, but clonal replication is less pronounced in mountain populations. Removal of clonal replicates reduces the autocorrelation for short lags and reverses the sign of the difference between mountain and Piedmont correlograms

The Fitness Consequences Of Multiple‐Locus Heterozygosity: The Relationship Between Heterozygosity And Growth Rate In Pitch Pine (Pinus Rigida Mill.)

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137487/1/evo05853.pd

Intertribal gene flow between the Ye'cuana and Yanomama: Genetic analysis of an admixed village

Genetic exchange with a neighboring village of Ye'cuana Indians had introduced two alleles, Di a and ACP a , into the Yanomama Indian village of Borabuk. After several generations, these alleles had reached frequencies of 0.08 and 0.10, respectively. These frequencies are puzzling because they are higher in Borabuk than in the Ye'cuana village from which they were derived. Single allele estimates of ancestral proportions obtained from either of these traits are biologically unrealistic and suggest that admixture is not a good explanation for genetic variation in Borabuk. Nevertheless, multiallelic admixture models are seen to produce credible estimates of ancestral proportions and to explain a large amount of allele frequency variation in Borabuk. When these results are compared with expectations derived from a formal pedigree analysis, good agreement is seen. Comparison of single allele estimates of ancestral proportions obtained from alleles at 11 loci, with multiallelic estimates obtained from the same 11 loci and with the pedigree-derived estimates, demonstrates the superiority of the multiallelic approach.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37623/1/1330610403_ftp.pd

Ecological specialization of Hawaiian Drosophila

The ecological overlap of three species of Hawaiian Drosophila: D. mimica D. kambysellisi , and D. imparisetae , has been investigated by analysis of the community matrix. The basic model is a Lotka-Volterra formulation, suitably expanded to include sexual dimorphism. We have also investigated equilibrium population sizes and stability properties of all possible communities which might be constructed from these species. Our findings are:Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47714/1/442_2004_Article_BF00345255.pd

The genetic implications of age-dependent penetrance in manic-depressive illness

An age dependent penetrance function was derived for manic-depressive illness, using age-of-onset data from sixty-one affected probands. The function used was a one-hit model, with earliest age-of-onset at about 14 yr, and a steadily increasing probability of manifesting the illness thereafter. The utility of the penetrance function for pedigree analysis was illustrated, using the families of the sixty-one probands. A sex-linked dominant model of inheritance was about eighty-nine times more likely than an autosomal dominant model, and both were far more likely than autosomal recessive or sex-linked recessive models. The more general single major locus model and the polygenic model cannot be ruled out, but would seem to be unnecessarily over-parameterized for the data at hand. The sex-linked dominant and autosomal dominant models were also compared, by means of the age specific morbidity risks and sibs and children. Both models provided a fairly close fit of expectation and observation, but the sex-linked model was preferable. Although the genetic conclusions cannot automatically be applied to other material, the analytical techniques should be useful elsewhere. Other uses of the penetrance function were indicated.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23042/1/0000614.pd

The demographic stability of small human populations

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/21866/1/0000270.pd

Discrete demographic models with density-dependent vital rates

The standard Leslie model of population growth in an age structured population is modified so as to incorporate density-dependent feedback control on each parameter of the standard projection matrix. Under fairly general conditions, the population converges to a stable age-distribution and a constant population size. This steady-state solution is uniquely determined by the parameters of the model. In general, fertility damping results in a flatter age-distribution than yielded by the undamped Leslie model. General survival damping results in the Leslie age-distribution. Post-infant survival damping results in a very steep age-distribution. For populations with high intrinsic growth rates, these differences in stable age-distributions are pronounced. For populations of low intrinsic growth rate, the patterns are the same, but the differences in stable age-distribution are more subtle. The age-distribution usually converges rapidly to the steady-state array, although population size generally takes longer to approach a stable value. Convergence properties are described for a series of cases which show periodicity. Such cases arise from “periodic” behavior of certain fertility-damping strategies, and ultimately approach a stable steady-state, although convergence may be very slow. Although the model is very general, it can be considerably simplified in practice. Special cases, which can be constructed, are the Malthusian (Leslie) model and the Logistic model. As a generality, the model is approximately Logistic, once the age-distribution approaches the steady-state array. One may use this fact for purposes of population projection.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47713/1/442_2004_Article_BF00553449.pd