Abstract
Biological invasions are impacting biota worldwide, and explaining why some taxa tend to become invasive is of major scientific interest. North American crayfish species, particularly of the family Cambaridae, are prominent invaders in freshwaters, defying the “tens rule” which states that only a minority of species introduced to new regions become established, and only a minority of those become invasive and pests. So far, success of cambarid invaders has largely been attributed to rapid maturation, high reproductive output, aggressiveness, and tolerance to pollution. We provide experimental evidence that females of one cambarid species particularly widespread in Europe, the spiny-cheek crayfish Orconectes limosus, are capable of facultative parthenogenesis. Such reproductive mode has never before been recognized in decapods, the most diverse crustacean order. As shown by analysis of seven microsatellite loci, crayfish females kept physically separated from males produced genetically homogeneous offspring identical with maternal individuals; this suggests they reproduced by apomixis, unlike those females which mated with males and had a diverse offspring. Further research is needed to clarify what environmental conditions are necessary for a switch to parthenogenesis in O. limosus, and what role it plays in natural crayfish populations. However, if such reproductive plasticity is present in other cambarid crayfish species, it may contribute to the overwhelming invasive success of this group.
Highlights
Crayfish are ecologically important benthic macroinvertebrates, and often act as keystone species in both standing and running waters [1]
No other crayfish proven to be capable of asexual reproduction is known from the wild
We provide evidence that the species is capable of facultative parthenogenesis, a reproductive mode not reported before in decapod crustaceans
Summary
Crayfish are ecologically important benthic macroinvertebrates, and often act as keystone species in both standing and running waters [1]. The introduction of North American crayfish to Europe has been successful, but has had serious conservational consequences, including the decimation of local crayfish populations by the crayfish plague pathogen introduced with them [2]. The first of those species, the spiny-cheek crayfish Orconectes limosus (Figure 1), became successfully established from a batch of 90 individuals released in 1890 to a fishpond in Pomerania (presently western Poland), and has since colonized at least 20 European countries [2,3]. No other crayfish (or any other decapod crustacean) proven to be capable of asexual reproduction is known from the wild
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