ACCOUNTING FOR BIOLOGICAL DIVERSITY 1

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72778/1/j.0014-3820.2003.tb00329.x.pd

The Origin and Distribution of Clonal Diversity in \u3ci\u3eAlsophila pometaria\u3c/i\u3e (Lepidoptera: Geometridae)

A survey of spatial and temporal variation in the frequency of electrophoretically defined genotypes in the geometrid moth Alsophila pometaria revealed a high diversity of uncommon or rare asexual genotypes and clinal distributions of two of the more common clones. There was substantial year-to-year variation in genotype frequencies in seven of eleven sites. Progeny tests have revealed that sexual reproduction is uncommon in two populations and that new asexual genotypes arise from the sexual population. The recurrent origin of asexual genotypes is likely to account for the high genetic and ecological diversity of the asexual contingent of this species’ populations, in contrast to the lower genetic diversity in some obligately asexual species in which such recruitment does not occur

Variation in Population Sex Ratio and Mating Success of Asexual Lineages of \u3ci\u3eAlsophila pometaria\u3c/i\u3e (Lepidoptera: Geometridae)

Populations of Alsophila pometaria (Harris) are largely gynogenetic and composed of asexual females that must mate with a conspecific male to reproduce. Within this asexual contingent, there are a variety of electrophoretically defined multilocus genotypes. In this study we found that populations differ in sex ratio. We also found that there is an indication of differential mating success among asexual genotypes in a population of A. pometaria

Survivorship and Growth of Sexually and Asexually Derived Larvae of \u3ci\u3eAlsophila pometaria\u3c/i\u3e (Lepidoptera: Geometridae)

A substantial body of theory is devoted to understanding the relative advantages of sexual and asexual reproduction. It is generally understood that asexual forms potentially have a higher rate of reproduction because they save the cost of producing males. The micro-evolutionary consequences of sexual and asexual reproduction are less clear. Sexual reproduction generates abundant genotypic diversity which may be adaptively advantageous (Williams 1975; Maynard Smith 1978). Asexual reproduction may perpetuate combinations of genes that are co-adapted (Templeton 1979), heterotic (Suomalainen et al. 1976; White 1979), or specialized (Vrijenhoek 1979, 1984). Thus, it is possible that the fitness of a sexual population may be lower than an asexual, in part, because recombination tends to break up especially favorable genotypes (Williams 1975; Hebert 1978). If it is generally observed that asexual reproduction has an immediate adaptive as well as a reproductive advantage, then it is difficult to see how sexual reproduction can be maintained by short-term advantages (Williams 1975). A comparison of closely related sexual and asexual forms is a promising avenue of research to evaluate experimentally the consequences of both modes of reproduction (Maynard Smith 1978). In this study, geometrid moth larvae (Alsophila pometaria) derived from both kinds of reproduction were reared on different host plants. The goal was to assess larval viability and growth in an ecologically relevant context and thus partially characterize the fitness of sexual and asexual reproduction

Variation in Population Sex Ratio and Mating Success of Asexual Lineages of \u3ci\u3eAlsophila pometaria\u3c/i\u3e (Lepidoptera: Geometridae)

Populations of Alsophila pometaria (Harris) are largely gynogenetic and composed of asexual females that must mate with a conspecific male to reproduce. Within this asexual contingent, there are a variety of electrophoretically defined multilocus genotypes. In this study we found that populations differ in sex ratio. We also found that there is an indication of differential mating success among asexual genotypes in a population of A. pometaria

Progress on the Origin of Species

Two new books on speciation update the classic texts by Mayr and Grant and help set the stage for a renaissance of research into one of the most important processes in evolutio

What doesn’t kill you will only make you more risk-loving: early life disasters and CEO behavior

The literature on managerial style posits a linear relation between a CEO's past experiences and firm risk. We show that there is a nonmonotonic relation between the intensity of CEOs’ early-life exposure to fatal disasters and corporate risk-taking. CEOs who experience fatal disasters without extremely negative consequences lead firms that behave more aggressively, whereas CEOs who witness the extreme downside of disasters behave more conservatively. These patterns manifest across various corporate policies including leverage, cash holdings, and acquisition activity. Ultimately, the link between CEOs’ disaster experience and corporate policies has real economic consequences on firm riskiness and cost of capital

Varying Herbivore Population Structure Correlates with Lack of Local Adaptation in a Geographic Variable Plant-Herbivore Interaction

Local adaptation of parasites to their hosts due to coevolution is a central prediction of many theories in evolutionary biology. However, empirical studies looking for parasite local adaptation show great variation in outcomes, and the reasons for such variation are largely unknown. In a previous study, we showed adaptive differentiation in the arctiid moth Utetheisa ornatrix to its host plant, the pyrrolizidine alkaloid-bearing legume Crotalaria pallida, at the continental scale, but found no differentiation at the regional scale. In the present study, we sampled the same sites to investigate factors that may contribute to the lack of differentiation at the regional scale. We performed field observations that show that specialist and non-specialist polyphagous herbivore incidence varies among populations at both scales. With a series of common-garden experiments we show that some plant traits that may affect herbivory (pyrrolizidine alkaloids and extrafloral nectaries) vary at the regional scale, while other traits (trichomes and nitrogen content) just vary at the continental scale. These results, combined with our previous evidence for plant population differentiation based on larval performance on fresh fruits, suggest that U. ornatrix is subjected to divergent selection even at the regional scale. Finally, with a microsatellite study we investigated population structure of U. ornatrix. We found that population structure is not stable over time: we found population differentiation at the regional scale in the first year of sampling, but not in the second year. Unstable population structure of the herbivore is the most likely cause of the lack of regional adaptation