Someone like me: Size-assortative pairing and mating in an Amazonian fish, sailfin tetra Crenuchus spilurus

Abstract

In the absence of constraints, preference for larger mates is expected to evolve, as larger individuals are typical of higher potential fitness. Large females are often more fecund and carry larger eggs (which result in higher number and better quality of offspring), whereas large males usually have more conspicuous ornaments and are better at defending resources. However, intrasexual competition can constrain the access to larger partners, especially when opportunities for mate takeover abound. Here we investigate the relationship between individual’s size and mate choice in relation to one’s own size and their respective mate’s size using the sailfin tetra, a sexually dimorphic Amazonian fish species. We show that ornaments of larger males are exponentially more conspicuous, and larger females are more fecund and carry larger eggs. Contrary to expectation, neither males nor females associated for longer with the larger of two offered potential mates. Instead, individuals of both genders chose opposite-sex individuals of similar sizes to themselves. Additionally, similar-sized pairs were more likely to spawn than couples with higher size asymmetries. Grounded on field observations, we propose that prudent choice should be particularly important in this system, since courtship is long (often taking several days), which offers opportunities for mate takeover. Intrasexual competition, however, cannot readily explain female choice for similar-sized males. We thus suggest that such preference might be best explained by avoidance of filial cannibalism.

Mate Choice and Size-Assortative Mating in the Climbing Perch Anabas testudineus (Actinopteri: Anabantidae)

“…С другой стороны, в некоторых случаях анабас нерестится лишь единожды за сезон и тогда можно говорить про моногамию уже безо всяких оговорок. Родительская забота также неизвестна у этих рыб [46], что в целом нетипично для моногамных видов [11]. Для выяснения того, какая из систем спаривания наиболее типична для ползуна, а также для выявления факторов влияния на нее необходимы исследования, в которых будет изучено размножение в больших группах и на протяжении хотя бы одного сезона.…”

“…Предполагается, что при наличии выбора и при отсутствии ограничений животное предпочитает крупного партнера, поскольку размер тела коррелирует с приспособленностью. Однако соразмерность также имеет ряд плюсов и потенциальных преимуществ, влияющих на выбор [11,12].…”

Ecologia Comportamental Evolutiva Aplicada a Peixes De Riacho

“…Machos maiores possuem ornamentos exponencialmente mais conspícuos (Borghezan et al 2019). As nadadeiras dorsal e anal se tornam proporcionalmente cada vez maiores à medida que o indivíduo cresce.…”

Assortative mating for reproductive timing affects population recruitment and resilience in a quantitative genetic model

“…This correlation could occur through mechanisms such as (1) mate choice based on phenotype; (2) fine‐scale temporal or spatial autocorrelation of phenotypes, including cases where space or time are considered as ‘traits’; (3) phenotypic changes over time, resulting in an increase in phenotypic correlations between mates; or (4) by patterns of selection on the pool of potential breeders (Jiang et al, 2013 ; Kopp et al, 2018 ; Rios Moura et al, 2021 ; Sørdalen et al, 2018 ). Assortative mating based on phenotype has been studied in a number of wild fish species, with the majority of examples around the world focused on the evolution of traits such as size (de Borghezan et al, 2019 ; Rios Moura et al, 2021 ; Rueger et al, 2016 ) or color (Utagawa et al, 2016 ). In the North Pacific Ocean, long‐term ecological monitoring studies on salmon (e.g., Barnett et al, 2019 ; Ford et al, 2015 ; Lin et al, 2017 ; May, 2022 ; Peterson et al, 2014 ) have found many cases of spatial and temporal assortative mating.…”