Male pygmy squid (Idiosepius paradoxus) attach their spermatophores to the outside of their partner’s body, and multiple males can make such deposits. This leaves females with the choice of which spermatophore to accept, and they show a distinct preference for the sperm packets that come from small males. Photo via Adobe Stock This is surprising, given what we know about large, dominant males and females’ general inclination towards them. But small-statured males are much faster
Nazca boobies are ground-nesting colonial seabirds that exhibit unique pseudomothering behaviour. In any given year, there are reproductive females whose nests have failed. While busy parents are off foraging for food for their nestlings, which can take a long time, depending on the availability of resources in a specific year, these females, and sometimes males too, pay “visits” to unattended chicks. These visits can last for varied amounts of time, from one minute to over
Mouth-brooding female cichlids (family Cichlidae) are in control of both pre- and post-mating sexual selection. In this highly specialized mating system, females gather up their extruded eggs and brood them in their mouths while soliciting sperm donations from select males. It’s like having several males ejaculate into your mouth in quick succession so that the most competitive sperm fertilizes the eggs. It’s worth noting that this kind of mouth-brooding strategy is markedly different from most
Environmental variation can wreak havoc on animals that use auditory signals to find mates. Ever tried to carry on a conversation with a potential mate in a noisy nightclub? Have you had much success in legitimate communication with deafening music and background chatter? I didn’t think so. Imagine the struggles faced by animals that depend on communication via mating vocalizations against noisy backdrops. Even the most basic environmental perturbations can have profound effects on the
Externally fertilizing fish provide several fascinating examples of cryptic female choice at work. In these systems, females lay their eggs in nests on the floor of their aquatic habitat, and males fertilize them externally. Congeneric (two separate species belonging to the same genus) Atlantic salmon and Atlantic trout (Salmo salar and S. trutta respectively) have overlapping habitats throughout most of their natural ranges. Photo via Adobe Stock These two fish species can successfully interbreed, although
In some of the more simplistic cases of cryptic female choice, females prove unable to discern a good mate from a bad one during pre-coital activities. In many insects it’s extremely difficult to tell a male from a female, much less distinguish between a high-quality male partner and a low-quality one. There isn’t a whole lot of “getting to know you” time prior to the copulatory event. In the insect world there are no long
The parenting hypothesis posits that first-time moms (moms who haven’t given birth) will allonurse unrelated offspring as a means by which to gain experience and skill for when the “real thing” occurs. Photo via Adobe Stock This kind of behaviour is observed in many primate species, such as Japanese macaques, in which both related and unrelated females will suckle newborns. If a female is pregnant for the first time and she’s in her last few