Smelling home can prevent dispersal of reef fish larvae

Abstract

Many marine fish and invertebrates show a dual life history where settled adults produce dispersing larvae. The planktonic nature of the early larval stages suggests a passive dispersal model where ocean currents would quickly cause panmixis over large spatial scales and prevent isolation of populations, a prerequisite for speciation. However, high biodiversity and species abundance in coral reefs contradict this panmixis hypothesis. Although ocean currents are a major force in larval dispersal, recent studies show far greater retention than predicted by advection models. We investigated the role of animal behavior in retention and homing of coral reef fish larvae resulting in two important discoveries: (i) Settling larvae are capable of olfactory discrimination and prefer the odor of their home reef, thereby demonstrating to us that nearby reefs smell different. (ii) Whereas one species showed panmixis as predicted from our advection model, another species showed significant genetic population substructure suggestive of strong homing. Thus, the smell of reefs could allow larvae to choose currents that return them to reefs in general and natal reefs in particular. As a consequence, reef populations can develop genetic differences that might lead to reproductive isolation.coral reef ͉ olfaction ͉ population genetics

Larval fish dispersal in a coral-reef seascape

“…Most larval reef fishes are strong swimmers with well-developed sensory systems that together may allow more limited dispersal than would be predicted based on advection and dispersion of passive particles 40 . Recently settled A. percula juveniles can detect olfactory signals in waters treated with anemones and leaves from rainforest trees, and can distinguish between water collected at locations adjacent to reefs and offshore water 41 .…”

High gene flow due to pelagic larval dispersal among South Pacific archipelagos in two amphidromous gastropods (Neritomorpha: Neritidae)

“…These pressures might not necessarily act in direct opposition. Whereas the former might select for behaviors that favor retention (for example, using chemical cues to stay near natal habitat, Gerlach et al, 2007), the latter might select for developmental and physiological changes that allow for delayed metamorphosis if necessary (as was suggested for habitat specialists in a recent survey of the literature, Bishop et al, 2006).…”

Humic Acid Interferes with Species Recognition in Zebrafish (Danio rerio)

“…From position records taken every 10 s, we calculated how often each fish selected a given stimulus. Water association time is widely used as a measure of preference in studies of kin recognition, shoaling preferences, and mate choice in laboratory studies on zebrafish (Rosenthal and Ryan 2005;Gerlach and Lysiak 2006;Gerlach et al 2007) and poeciliids, including swordtails (see Wong and Rosenthal 2005 and references therein). We calculated the difference between the total number of observations in which a test fish was in the lane of the flume associated stimulus A or B, and tested whether that difference was significant from zero by using the Wilcoxon matched-pairs signed-ranks (WSR) test.…”