Spatial sorting according to body size and shape explains variation in spawning migration distance between species, sexes and individuals of cyprinid fish

• Spatial sorting is a process in which individuals in a moving population are sorted in space according to phenotypic traits that influence their dispersal capabilities. Although the spatial sorting hypothesis was originally developed to explain patterns in the distribution of phenotypes within populations and species, we propose that under certain conditions, differences in dispersal capacity due to phenotypic traits may also contribute to spatial arrangement of different species. Dispersal capacity in fish is often related to size and slimness. Here, we evaluate the hypothesis that spawning migrating fish will be spatially sorted along the length of a river according to species, sex, and individual phenotype. We marked 457 and 493 spawning migrating ide (Leuciscus idus) and roach (Rutilus rutilus) individuals with PIT-tags and followed their migration along a stream using multiple PIT-reader stations. All marked ide individuals remained in the lower reaches of the stream. Roach, which are smaller and slimmer than ide, migrated further. Roach males, which are slimmer than females, migrated further. Among female roaches, slimmer individuals migrated further than stouter individuals. Although alternative mechanisms are possible, all these patterns are accounted for with a non-adaptive spatial sorting regime. This study illustrates that individuals in migrating populations distribute non-randomly in rivers, which has important implications regarding modifications to connectivity.

Ämnesord

NATURVETENSKAP  -- Biologi -- Ekologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Ecology (hsv//eng)

Nyckelord

Evolutionary Biology

Evolutionsbiologi

Akvatisk ekologi

Aquatic Ecology

Publikations- och innehållstyp

vet (ämneskategori)

ovr (ämneskategori)