Alternatives to Robinson and Redford's method of assessing overharvest from incomplete demographic data

Conservation biologists often must make decisions about the sustainability of harvest rates based on minimal demographic information. To assist them Robinson anti Redford (1991) formulated a method to estimate maximum rates of production which could be used to detect overharvesting based on only age at first reproduction, fecundity, and maximum longevity. By assuming constant adult survival we reduced the Euler equation to a simple form that allows calculation of population growth from the same minimal demographic data, brit that can incorporate empirical prereproductive and adult survival rates if available. With this formula, we computed growth rates rising various explicit survival schedules, and we compared these rates and those from Robinson and Redford's (1991) method to rates calculated from 19 relatively complete mammalian life tables gleaned from the literature. When we applied our method (assuming 1% survival to maximum longevity) and that of Robinson and Redford (1991) to the same minimal demographic data, we found that our growth rates were closer to those from complete life tables. We therefore reexamined the data of Fa et al (1995) and Fitzgibbon et al. (1995), who analyzed overharvesting of several populations of commercially exploited African mammals based on Robinson and Redford's (1991) methods Our reanalysis indicates that several additional populations may be overharvested. Our analysis also suggests that data on survival to age at first reproduction improves estimates of population growth rates more than data on age-specific adult survival. Regardless of the method, approximate growth rates based on incomplete life tables can be used to detect when populations are overharvested, brit one should not conclude that harvest rates are sustainable when they are less than approximate production rates because simplifying assumptions often lend to overestimates

Introgressive hybridization as a mechanism for species rescue

Rapid evolution on ecological time scales can play a key role in species responses to environmental change. One dynamic that has the potential to generate the diversity necessary for evolution rapid enough to allow response to sudden environmental shifts is introgressive hybridization. However, if distinct sub-species exist before an environmental shift, mechanisms that impede hybridization, such as assortative mating and hybrid inferiority, are likely to be present. Here we explore the theoretical potential for introgressive hybridization to play a role in response to environmental change. In particular, we incorporate assortative mating, hybrid inferiority, and demographic stochasticity into a two-locus, two-allele population genetic model of two interacting species where one locus identifies the species and the other determines how fitness depends on the changing environment. Simulation results indicate that moderately high values for the strength of assortative mating will allow enough hybridization events to outweigh demographic stochasticity but not so many that continued hybridization outweighs backcrossing and introgression. Successful introgressive hybridization also requires intermediate relative fitness at the allele negatively affected by environmental change such that hybrid survivorship outweighs demographic stochasticity but selection remains strong enough to affect the genetic dynamics. The potential for successful introgression instead of extinction with greater environmental change is larger with monogamous rather than promiscuous mating due to lower stochasticity in mating events. These results suggest species characteristics (e.g., intermediate assortative mating and mating systems with low variation in mating likelihood) which indicate a potential for rapid evolution in response to environmental change via introgressive hybridization

Code for Watts et al. “Environmental cue integration and phenology in a changing world” Integrative and Comparative Biology

Code used for model in Watts et al. “Environmental cue integration and phenology in a changing world” in Integrative and Comparative Biology; provided as an .RMD file (a R Markdown file created using RStudio, R version 4.0.5)

Evolutionary rescue beyond the models

Laboratory model systems and mathematical models have shed considerable light on the fundamental properties and processes of evolutionary rescue. But it remains to determine the extent to which these model-based findings can help biologists predict when evolution will fail or succeed in rescuing natural populations that are facing novel conditions that threaten their persistence. In this article, we present a prospectus for transferring our basic understanding of evolutionary rescue to wild and other non-laboratory populations. Current experimental and theoretical results emphasize how the interplay between inheritance processes and absolute fitness in changed environments drive population dynamics and determine prospects of extinction. We discuss the challenge of inferring these elements of the evolutionary rescue process in field and natural settings. Addressing this challenge will contribute to a more comprehensive understanding of population persistence that combines processes of evolutionary rescue with developmental and ecological mechanisms

Legal Standards and Significance of DNA Evidence

This is the publisher's version. It is also available electronically from: http://www2.lib.ku.edu:2048/login?url=http://proquest.umi.com/pqdweb?did=14389935&sid=1&Fmt=4&clientId=42567&RQT=309&VName=PQDMost human biologists are aware of controversies regarding the use of DNA profiles in the courtroom. Much attention has been given to estimating the probability of obtaining matches between DNA samples from an innocent suspect and those from a crime scene, but considerably less attention has been given to the critical issue of determining the probability of guilt given a match. Using Bayes' rule and simple algebra, we develop a measure of the strength of DNA evidence that indicates the amount of incriminating evidence needed in combination with DNA match evidence to meet a given conviction standard. Based on current standards and practices, we use this measure to demonstrate that (1) the amount of non-DNA evidence needed to convict, given a DNA match, generally is quite small, even if errors can occur in the processing of DNA evidence: (2) DNA match evidence alone is insufficient to convict, even for the lowest recognized conviction standards; (3) failure to match DNA evidence samples should be exculpatory unless laboratory proficiency is poor; and (4) if errors in handling evidentiary samples occur (even rarely) that tend to produce a false DNA match, then the legal significance of DNA evidence is remarkably insensitive to estimates of chance match probability

Legal Standards and the Significance of DNA Evidence

Most human biologists are aware of controversies regarding the use of DNA profiles in the courtroom. Much attention has been given to estimating the probability of obtaining matches between DNA samples from an innocent suspect and those from a crime scene, but considerably less attention has been given to the critical issue of determining the probability of guilt given a match. Using Bayes’ rule and simple algebra, we develop a measure of the strength of DNA evidence that indicates the amount of incriminating evidence needed in combination with DNA match evidence to meet a given conviction standard. Based on current standards and practices, we use this measure to demonstrate that (1) the amount of non-DNA evidence needed to convict, given a DNA match, generally is quite small, even if errors can occur in the processing of DNA evidence; (2) DNA match evidence alone is insufficient to convict, even for the lowest recognized conviction standards; (3) failure to match DNA evidence samples should be exculpatory unless laboratory proficiency is poor; and (4) if errors in handling evidentiary samples occur (even rarely) that tend to produce a false DNA match, then the legal significance of DNA evidence is remarkably insensitive to estimates of chance match probability

Probability of Fixation in a Heterogeneous Environment

We investigate the probability of fixation of a new mutation arising in a metapopulation that ranges over a heterogeneous selective environment. Using simulations, we test the performance of several approximations of this probability, including a new analytical approximation based on separation of the timescales of selection and migration. We extend all approximations to multideme metapopulations with arbitrary population structure. Our simulations show that no single approximation produces accurate predictions of fixation probabilities for all cases of potential interest. At the limits of low and high migration, previously published approximations are found to be highly accurate. The new separation-of-timescales approach provides the best approximations for intermediate rates of migration among habitats, provided selection is not too intense. For nonzero migration and relatively strong selection, all approximations perform poorly. However, the probability of fixation is bounded above and below by the approximations based on low and high migration limits. Surprisingly, in our simulations with symmetric migration, heterogeneous selection in a metapopulation never decreased—and sometimes substantially increased—the probability of fixation of a new allele compared to metapopulations experiencing homogeneous selection with the same mean selection intensity

The sterile insect technique is protected from evolution of mate discrimination

Background The sterile insect technique (SIT) has been used to suppress and even extinguish pest insect populations. The method involves releasing artificially reared insects (usually males) that, when mating with wild individuals, sterilize the broods. If administered on a large enough scale, the sterility can collapse the population. Precedents from other forms of population suppression, especially chemicals, raise the possibility of resistance evolving against the SIT. Here, we consider resistance in the form of evolution of female discrimination to avoid mating with sterile males. Is resistance evolution expected? Methods We offer mathematical models to consider the dynamics of this process. Most of our models assume a constant-release protocol, in which the same density of males is released every generation, regardless of wild male density. A few models instead assume proportional release, in which sterile releases are adjusted to be a constant proportion of wild males. Results We generally find that the evolution of female discrimination, although favored by selection, will often be too slow to halt population collapse when a constant-release implementation of the SIT is applied appropriately and continually. The accelerating efficacy of sterile males in dominating matings as the population collapses works equally against discriminating females as against non-discriminating females, and rare genes for discrimination are too slow to ascend to prevent the loss of females that discriminate. Even when migration from source populations sustains the treated population, continued application of the SIT can prevent evolution of discrimination. However, periodic premature cessation of the SIT does allow discrimination to evolve. Likewise, use of a ‘proportional-release’ protocol is also prone to escape from extinction if discriminating genotypes exist in the population, even if those genotypes are initially rare. Overall, the SIT is robust against the evolution of mate discrimination provided care is taken to avoid some basic pitfalls. The models here provide insight for designing programs to avoid those pitfalls

Optimizing selection for function-valued traits

Abstract We consider a function-valued trait z(t) whose pre-selection distribution is Gaussian, anda fitness function W that models optimizing selection, subject to certain natural assump-tions. We show that the post-selection distribution of z(t) is also Gaussian, compute theselection differential, and derive an equation that expresses the selection gradient in terms of the parameters of W and of the pre-selection distribution. We make no assumptions onthe nature of the "time " parameter t