New Fish Species Offers Literal Take on ‘Hooking Up’

Fishing hooks aren’t the only hooks found in east-central Mexican waters.

一种淡水鱼没有描述rth Carolina State University researcher has several interesting – and perhaps cringe-inducing – characteristics, including a series of four hooks on the male genitalia.

Females of the new species – the llanos mosquitofish, orGambusia quadruncus– also have distinguishing characteristics, including a colorful anal spot.

A paper describing the new species, which lives in a diversity hotspot and seemingly branched off from its closest relative more than one million years ago, appears in theJournal of Fish Biology.

Dr. Brian Langerhans, assistant professor of biology at NC State and the lead author of the paper, says that these interesting characteristics may play important roles in mating control and success.

While more research is needed, Langerhans says that four-hooked genitalia on males can serve a purpose when females attempt to block or restrict mating attempts.

“Typically, reproduction is more costly in females, so females favor ways of reducing mating with ‘lower quality’ males,” Langerhans says, “but reproduction is cheap in males and so selection favors ways of mating with as many females as possible. InGambusia, some females, includingG. quadruncus，具有演进的修改，该修改似乎用作阻塞装置 - 基本上是一个大球的组织，阻断了雄性巨孔尖端的大多数生殖器孔隙。因此，女性必须行为允许男性与伴侣或男性不得不演变反应以避免这个问题。“

Langerhans说，四钩的生殖器可能是反应反应。

“Having four hooks on the gonopodium may provide a means of overcoming female resistance, latching on to the gonopore and transferring sperm in a manner that facilitates effective sperm transfer. Or it may serve to stimulate the female in a manner that causes responses in the female that facilitate effective sperm transfer,” Langerhans says.

Somewhat similarly, the colorful anal spot on females appears to serve as a signal that only certain males are desired for mating.

“不同的物种特异性的女性肛门斑点似乎通过向男性的位置向男性的位置来影响男性交配行为，有时表明女性的生殖状态，以及将自己物种的鱼类与其他物种的鱼类区分开来减少朗格汉斯说，昂贵的交叉育种，这可能导致健身减少的鱼类。““所以它可能是那个G. quadruncusevolved different anal spots to help reduce interspecies matings and possible formation of hybrids.”

– kulikowski –

Note to editors: An abstract of the paper follows.

Gambusia Quadruncus（Cyprinodontiformes：Poeciliidae）：来自墨西哥东部的新品种蚊虫

Authors: Brian Langerhans, North Carolina State University; et al

Published: September 2012, inJournal of Fish Biology

Abstract:Gambusia quadruncusn. sp., the llanos mosquitofish, is described from east-central Mexico. The region inhabited by the species represents a hotspot of diversity ofGambusia, andG. quadruncussometimes coexists with at least three congeners. The species differs from its closest relative,Gambusia affinis, in several characteristics with plausible effects on reproductive isolation, e.g. body size, body and fin morphology, male genital morphology (distal tip of gonopodium) and female anal spot morphology (colouration near the urogenital sinus). Moreover, combined analysis of mitochondrial and nuclear gene sequence data (c. 2158 total base pairs) indicates reciprocal monophyly ofG. quadruncus及其妹妹种类G. Affinis., with levels of genetic divergence suggesting the two species diverged from one another over a million years ago. The origin ofG. quadruncusmay reflect a vicariant event associated with Pliocene orogenesis in the Tamaulipas Arch and a frontal section of the Sierra Madre Oriental (Lleran Mesas).Gambusia quadruncusinhabits a variety of freshwater habitats across several river drainages, with its range spanning at least 350 km from north to south, covering over 25 000 km2. A key to aid identification of the species is provided.