Genetically separate populations of the ocean-skater Halobates sericeus (Heteroptera: Gerridae) have been maintained since the late Pleistocene

Abstract

The oceanic water strider (or ocean-skater) Halobates sericeus Eschscholtz has a disjunct distribution in the Pacific Ocean, with northern and southern populations widely separated by an equatorial zone. It is sensitive to sea surface conditions and, consequently, its distribution and population structure may provide an insight into environmental changes on the ocean surface on both recent and historical time scales. We assessed the genetic diversity and population structure of H. sericeus in the Pacific Ocean using three gene markers -cytochrome oxidase subunit I (COI), elongation factor 1a and internal transcribed spacer 1 (ITS-1). These markers indicate that both populations are evolutionarily distinct with limited gene flow, having separated 20 000-50 000 years ago. This suggests that physical conditions and/or biotic interactions on the surface of the Pacific Ocean have provided significant barriers to gene flow since the late Pleistocene or earlier, creating biotic stability over large geographical and temporal scales in spite of a long history of global climate change.

Endorsing Darwin: global biogeography of the epipelagic goose barnaclesLepas spp. (Cirripedia, Lepadomorpha) proves cryptic speciation

“…The separate Oregon coast subgroup supports the importance of the Pacific gyre systems for L. anatifera , however, just opposite to L. anserifera (see below). Species of the ocean skater Halobates , as well as genetically discriminated populations of H. micans and Halobates sericeus Eschscholtz, 1822 (Andersen et al ., ; Leo, Cheng & Sperling, ), also prove the existence of disjunct northern and southern populations in the Pacific. The rafting bryozoan Membranipora shows a much higher degree of regionalization, but the northern and the southern Pacific clades are clearly separated (Schwaninger, ).…”

“… Speciation in the pelagic realm has its roots in geological time (for example, see Andersen et al ., ; Fraser et al ., ; Norris & Hull, ; Leo et al ., ). The hypothesis of rapid diversification and regionalization of zooplanktic species (Peijnenburg & Goetze, ) cannot be regarded as a general valid rule. Allopatric speciation is of prime importance, even in apparently barrierless oceanic regions like the southern Pacific.…”

Endorsing Darwin – Global biogeography of the epipelagic goose barnacles Lepas spp. (Cirripedia, Lepadomorpha) proves cryptic speciation

“…(1) Speciation in the pelagic realm has its roots in geological time (see for example also Andersen et al, 2000;Fraser et al, 2009;Norris & Hull, 2011;Leo et al, 2012). The p r e p r i n t postulate of rapid diversification and regionalisation of zooplanktic species (Peijnenburg & Goetze, 2013) cannot be regarded as general valid rule.…”

“…However, our findings seem to support the importance of the Pacific gyre systems for L. anatifera -just opposite than in L. ansifera (see below). Species of the ocean skater Halobates as well as genetically discriminated populations of the species H. micans and H. sericeus, (Andersen et al, 2000) (Leo et al, 2012), also prove disjunct northern and southern Pacific species, resp. populations.…”

Skaters of the seas – comparative ecology of nearshore and pelagicHalobatesspecies (Hemiptera: Gerridae), with special reference to Japanese species

“…Results from molecular analyses suggest very limited gene flow between the two populations Leo et al 2012). However, specimens collected close to the equator in the central and eastern Pacific Ocean (about 165Á1458W, 1308W, 1108W, 808W in Figure 6A) suggest that it could penetrate into the habitat of H. micans.…”