Premating Reproductive Barriers between Hybridising Cricket Species Differing in Their Degree of Polyandry

Understanding speciation hinges on understanding how reproductive barriers arise between incompletely isolated populations. Despite their crucial role in speciation, prezygotic barriers are relatively poorly understood and hard to predict. We use two closely related cricket species, Gryllus bimaculatus and G. campestris, to experimentally investigate premating barriers during three sequential mate choice steps. Furthermore, we experimentally show a significant difference in polyandry levels between the two species and subsequently test the hypothesis that females of the more polyandrous species, G. bimaculatus, will be less discriminating against heterospecific males and hence hybridise more readily. During close-range mating behaviour experiments, males showed relatively weak species discrimination but females discriminated very strongly. In line with our predictions, this discrimination is asymmetric, with the more polyandrous G. bimaculatus mating heterospecifically and G. campestris females never mating heterospecifically. Our study shows clear differences in the strength of reproductive isolation during the mate choice process depending on sex and species, which may have important consequences for the evolution of reproductive barriers

Data from: Diverse reproductive barriers in hybridising crickets suggests extensive variation in the evolution and maintenance of isolation

Reproductive barriers reduce gene flow between populations and maintain species identities. A diversity of barriers exist, acting before, during and after mating. To understand speciation and coexistence, these barriers need to be quantified and their potential interactions revealed. We use the hybridising field crickets Gryllus bimaculatus and G. campestris as a model to understand the full compliment and relative strength of reproductive barriers. We find that males of both species prefer conspecific females, but the effect is probably too weak to represent a barrier. In contrast, prezygotic barriers caused by females being more attracted to conspecific male song and preferentially mounting and mating with conspecifics are strong and asymmetric. Postzygotic barriers vary in direction; reductions in fecundity and egg viability create selection against hybridisation, but hybrids live longer than pure-bred individuals. Hybrid females show a strong preference for G. bimaculatus songs, which together with a complete lack of hybridisation by G. campestris females, suggests that asymmetric gene flow is likely. For comparison, we review reproductive barriers that have been identified between other Gryllids and conclude that multiple barriers are common. Different species pairs are separated by qualitatively different combinations of barriers, suggesting that reproductive isolation and even the process of speciation itself may vary widely even within closely related groups

Mate choice experiment using wild-caught <i>G. campestris</i> and lab-reared <i>G. bimaculatus</i>.

<p>Generalised linear-mixed model analyses looking at the propensity of males to start singing, and the propensity of females to mount and mate within 10 minutes to con- and heterospecific partners (see main text for details). The <i>G. campestris</i> used in this experiment were wild-caught in 2009 and 2010. The <i>G. bimaculatus</i> were raised in the lab. Explanatory variables retained in the final model are in bold.</p

Mate choice experiment using only lab-reared crickets.

<p>Generalised linear-mixed model analyses looking at the propensity of males to start singing, and the propensity of females to mount and mate within 10 minutes to con- and heterospecific partners. The experimental set-up between the mate choice tests differed slightly. In this experiment each individual was tested against both a hetero- and conspecific partner and we controlled for presentation order (see main text for details). The <i>G. campestris</i> used in this experiment were the F1-generation from wild-caught individuals and reared in the lab in 2009. The <i>G. bimaculatus</i> were raised in the lab for several generations. Explanatory variables retained in the final model are in bold.</p

Mate choice experiments.

<p>Males and females of the two species were paired in con- and heterospecific pairs and the proportion of males starting courtship song (<b>A</b>, <b>D</b>), females mounted (<b>B</b>, <b>E</b>) and mated after 10 minutes (<b>C</b>, <b>F</b>). The top row (<b>A</b>–<b>C</b>) represents trials using wild-caught <i>G. campestri</i>s (2009 and 2010) of unknown age and mating status. The captive bred offspring of the wild-caught <i>G. campestri</i>s (2009) were used in a subsequent mate choice experiment (<b>D</b>–<b>F</b>) in which e.g., rearing condition, mating status and mating sequence could be controlled for (see main text for more details). Lab-reared <i>G. bimaculatus</i> were used for all trials.</p

Preferences and Perspectives of Black Male Barbershop Patrons on Receiving Health Care in Nontraditional Settings.

INTRODUCTION: Non-Hispanic Black men experience a disproportionate rate of morbidity and mortality from hypertension, cardiovascular disease, and other chronic conditions in the United States. Studies have demonstrated the efficacy of community-based health outreach in settings not traditionally utilized for health care. Understanding how potential future participants view health care services in nontraditional settings is a necessary step to ascertain the success of these interventions in the real world. Our study objective was to explore the preferences of Black male barbershop patrons regarding health care-provided services in these nontraditional settings. METHODS: We recruited patrons of a Black-owned barbershop in the San Francisco Bay Area. Study participants were asked to complete a survey assessing individual attitudes and preferences toward the idea of receiving health care services in traditional and nontraditional settings. RESULTS: Among non-Hispanic Black males (n=17), 81% agreed or strongly agreed that they would prefer to receive health care in traditional clinics. Receiving care at the pharmacy (56% agreed or strongly agreed) and the patients own home (53% agreed or strongly agreed) were the next most preferred locations. A minority of participants agreed or strongly agreed that they preferred to receive health care in nontraditional settings: 47% for barbershops, 19% for churches, and 6% for grocery stores. DISCUSSION: Participants expressed preference for traditional over nontraditional settings, despite listing barriers that may be addressed, in part, by nontraditional settings. One potential reason for this is simply a lack of familiarity. Establishing and normalizing nontraditional clinical settings may allow for enhanced acceptance within Black communities, ultimately increasing health care access