Sexually selected male weapon is associated with lower inbreeding load but higher sex load in the bulb mite

Elaborate sexually selected ornaments and armaments are costly but increase the reproductive success of their bearers (usually males). It has been postulated that high-quality males can invest disproportionately more in such traits, making those traits honest signals of genetic quality. However, genes associated with such traits may have sexually antagonistic effects on fitness. Here, using a bulb mite Rhizoglyphus robini, a species in which a distinct dimorphism exists between males in the expression of a sexually selected weapon, we compare inbreeding and gender load between lines derived from armed fighters and unarmed scramblers. After four generations of sib-mating, inbreeding depression for female fitness was significantly lower in fighter-derived lines compared to scrambler-derived lines, suggesting that fighter males had significantly higher genetic quality. However, outbred females from fighter-derived lines had significantly lower fitness compared to outbred females from scrambler-derived lines, demonstrating significant gender load associated with the presence of a sexually selected male weapon. Our results imply that under outbreeding, genetic benefits of mating with bearers of elaborate sexually selected traits might be swamped by the costs of decreased fitness of female progeny due to sexually antagonistic effects.     

Egg sac damage and previous egg sac production influence truncated parental investment in the wolf spider,Pardosa milvina

Life history theory predicts that iteroparous animals adaptively partition reproductive effort between current and future reproduction. When rearing costs of current offspring exceed the potential benefits, parental care should be terminated and deferred toward future reproduction. We tested two related predictions that follow from life history theory: (a) parents should be sensitive to offspring viability and withhold parental care if offspring survival probability drops and future reproductive opportunities are likely, and (b) parents should be less sensitive to offspring survival probability when future reproduction is unlikely and maximize parental care late in life. The wolf spider, Pardosa milvina, demonstrates extensive parental care; however, they may also abandon or cannibalize their egg sacs. We tested the effects of egg sac damage and production of a previous egg sac on egg sac abandonment and cannibalism decisions. Among four egg sac groups (1st egg sac intact, 1st egg sac damaged, 2nd egg sac intact, 2nd egg sac damaged), we daily monitored egg sac abandonment and cannibalism and measured differences in egg sac searching, protection, and grooming among removed and damaged egg sacs (N = 116 with 1st egg sac and 88 with 2nd egg sac). Females with first egg sacs abandoned and cannibalized damaged egg sacs significantly more compared to unmanipulated egg sacs; however, females with second egg sacs were insensitive to egg sac damage. Females also spent significantly more time protecting second egg sacs compared to first egg sacs and groomed damaged egg sacs significantly more than undamaged. These results support the general predictions of life history theory that indicate that abandonment and cannibalism should decrease with diminished future reproductive potential and that parents should be less sensitive to indicators of offspring survival probability late in life.     

Modern Portfolio Theory and the prudent hermaphrodite

Summary

Employment of Markowitz's Modern Portfolio Theory, economic models designed to predict the effect of variance and covariance on optimal investment allocation, may explain a wide variety of anomalies in reproductive biology. Natural selection appears to favor genetic diversity among offspring to a greater extent than is predicted by current theory. Consideration of the possible increase in fitness by reducing the covariance among offspring may help explain a variety of phenomena from multiple mating to the evolution of recombination (i.e., overcoming “the cost of meiosis”). Modern Portfolio Theory also make novel predictions as to when hermaphrodites should prefer the male vs. female role, i.e., engage in egg- vs. sperm-trading. It predicts that the sexual role with the lower variance in reproductive success will be preferred in hermaphrodites. This contradicts Bateman's principle that the male role is usually preferred due to energetic considerations but is consistent with Gillespie's principle. The available data suggest that mating hermaphrodites are risk-averse; gamete-trading whether of eggs or sperm is a strategy to reduce risk. In addition to overall variance, the skew of the distribution can be used to predict the mating systems of hermaphrodites and thus clarify the factors that are responsible for observed patterns of sex allocation and sexual conflict. The reduction of covariance among offspring may also help resolve “Williams' paradox”; that the observed distribution of dieoecy vs. simultaneous hermaphroditism in the Animal Kingdom cannot be explained by the prevailing models of the evolution of hermaphroditism.     

Newspaper Portrayals,Local Policies,and Dog-Supportive Public Space: Who's Wagging Whom?

ABSTRACT

Dog-walking promotes physical activity and positive social interactions, and thus dog-walking has implications for people's physical and mental health. As a result, experts in public health have endorsed designing and managing public space to support dog-walking. Nevertheless, the presence of dogs in public space is subject to negotiation and can be controversial. Generally, municipal governments or local councils exercise political jurisdiction over both dogs and public space. As a case study, we systematically collected and analyzed a local newspaper's portrayals of issues relating to dog-walking in public space. Our purpose was to understand how public and policy agendas were being represented by local media, during a period of time when local policies on dog ownership and dog-supportive public space were being reviewed and revised. The analysis involved three phases: 1) thematic content analysis; 2) issue framing analysis; and 3) policy analysis. Thematically, we found that social conflict predominated. In terms of issue framing, local policy and individual dog owner behavior were both problematized. Over time, the policy agenda evolved to emphasize the design and management of public space, especially park land. Policy-makers presented this emphasis on public space as a proactive strategy to reduce social conflict and to promote compliance with existing rules on dog ownership. When it comes to promoting dog-walking to benefit animal welfare and human health, our findings underscore the importance of paying close attention to local policies and media coverage. In fact, we found that endogenous conflict and public controversies can actually represent significant opportunities to bring about positive changes in the lives of humans and nonhuman animals.     

Building cross‐cultural coalitions: A case‐study of the Black‐Korean Alliance and the Latino‐Black Roundtable

A case‐study is presented of two Los Angeles‐based cross‐cultural coalitions, the Black‐Korean Alliance [BKA] and the Latino‐Black Roundtable [LBR]. An analysis of the development and eventual dissolution of these two coalitions is presented against the backdrop of the history of relations between the African‐American, Korean‐American and Latino communities of Los Angeles. The central issues leading to the breakup of the two coalitions were: lack of resources, internal power dynamics between coalition partners, nationalistic factions within the broader communities, cross‐cultural dynamics between coalition members, the use of a dialogue model to frame coalition activities, and the analysis of intergroup relations underlying the formation of the coalitions. The applied and theoretical implications of the research are discussed.     

Manipulating national identity: the strategic use of rhetoric by supporters and opponents of the ‘Cronulla riots’ in Australia

This research explores the role of opinion-based groups in understanding responses to racist violence such as the 2005 Cronulla riots in Australia. Traditionally, explanations of collective action in social psychology and sociology focus on conflict between broad social categories. We propose that the responses to the riots can be understood not only as inter-group conflict between Muslims and non-Muslims, or an in-group argument amongst non-Muslims, but as a bona fide inter-group conflict between supporters and opponents of the riots. We argue that these groups use rhetoric in attempts to claim dominant status within society by aligning their identities with positively valued social categories such as ethnicities and national identities. The analysis of rhetoric from the groups supporting and opposing the riots demonstrates consistent, albeit contested, attempts to align support for the riot with the Australian national category in conflict with countervailing attempts to align opposition to the riot with the same national category.     

Movements,moments and moods. Generation as unity and strife in Peruvian migration

This article discusses the meaning and use of generation in migration studies. It argues that the term is useful to examine how migrants create linkages between their pre- and post-migration lives. The article draws on Mannheim's notions of ‘generational units’ and ‘fresh contact’ to scrutinize how Peruvians engage resources from their previous lives in Peru to achieve social mobility in the USA, Japan, Spain and Argentina. In particular, the article focuses on the role of education, ethnicity and conflict in Peruvians’ efforts to create support networks and form migrant institutions. It suggests that generational units grow out of migrants’ shared experience of mobilizing the same resource to establish fresh contact with their receiving society. The article concludes that while generational belonging can generate a strong sense of solidarity among some groups of migrants, this often happens at the cost of the unity and inclusion of the migrant community at large.     

Old‐male paternity advantage is a function of accumulating sperm and last‐male precedence in a butterfly

Old‐male mating advantage has been convincingly demonstrated in Bicyclus anynana butterflies. This intriguing pattern may be explained by two alternative hypotheses: (i) an increased aggressiveness and persistence of older males during courtship, being caused by the older males' low residual reproductive value; and (ii) an active preference of females towards older males what reflects a good genes hypothesis. Against this background, we here investigate postcopulatory sexual selection by double‐mating Bicyclus anynana females to older and younger males, thus allowing for sperm competition and cryptic mate choice, and by genotyping the resulting offspring. Virgin females were mated with a younger virgin (2–3 days old) and afterwards an older virgin male (12–13 days old) or vice versa. Older males had a higher paternity success than younger ones, but only when being the second (=last) mating partner, while paternity success was equal among older and younger males when older males were the first mating partner. Older males produced larger spermatophores with much higher numbers of fertile sperm than younger males. Thus, we found no evidence for cryptic female mate choice. Rather, the findings reported here seem to result from a combination of last‐male precedence and the number of sperm transferred upon mating, both increasing paternity success.     

Using multilevel models to identify drivers of landscape‐genetic structure among management areas

Landscape genetics offers a powerful approach to understanding species' dispersal patterns. However, a central obstacle is to account for ecological processes operating at multiple spatial scales, while keeping research outcomes applicable to conservation management. We address this challenge by applying a novel multilevel regression approach to model landscape drivers of genetic structure at both the resolution of individuals and at a spatial resolution relevant to management (i.e. local government management areas: LGAs) for the koala (Phascolartos cinereus) in Australia. Our approach allows for the simultaneous incorporation of drivers of landscape‐genetic relationships operating at multiple spatial resolutions. Using microsatellite data for 1106 koalas, we show that, at the individual resolution, foliage projective cover (FPC) facilitates high gene flow (i.e. low resistance) until it falls below approximately 30%. Out of six additional land‐cover variables, only highways and freeways further explained genetic distance after accounting for the effect of FPC. At the LGA resolution, there was significant variation in isolation‐by‐resistance (IBR) relationships in terms of their slopes and intercepts. This was predominantly explained by the average resistance distance among LGAs, with a weaker effect of historical forest cover. Rates of recent landscape change did not further explain variation in IBR relationships among LGAs. By using a novel multilevel model, we disentangle the effect of landscape resistance on gene flow at the fine resolution (i.e. among individuals) from effects occurring at coarser resolutions (i.e. among LGAs). This has important implications for our ability to identify appropriate scale‐dependent management actions.