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The biological changes caused by autotriploidy are poorly studied in animals. To investigate this issue in depth, we compared genetics, morphology, life history, ecology and behaviour of the triploid marbled crayfish and its diploid parent, slough crayfish Procambarus fallax. We performed a meta-analysis of our data and literature data. Our COI based molecular tree, consisting of 27 species of Cambaridae, confirmed the close taxonomic relationship between marbled crayfish and P. fallax. Comparison of both crayfish revealed similarities in mitochondrial gene sequences, morphological characters, colouration, body proportions and behaviours. Considerable differences were recorded with respect to chromosome number in somatic cells, haploid genome size, DNA methylation level, body size, fecundity, longevity, population size structure, invasiveness, and the range of inhabited biomes. These differences have dimensions that are otherwise only observed between species supporting earlier proposed raising of marbled crayfish from P. fallax forma virginalis to a new species named Procambarus virginalis. Particularly noteworthy is the enhancement of the fitness traits that probably resulted from evolutionary changes in gene expression. These alterations and the transition from sexual reproduction to parthenogenesis are likely responsible for the increased invasiveness of marbled crayfish in tropical to cold-temperate biomes.

Despite the importance of aquatic symbionts in community organization, often little is known about the relative role of host and environmental characteristics on symbiont abundance. We investigated the importance of environmental and host physical characteristics on the abundance of the branchiobdellidan, Branchiobdella kozarovi , on a population of narrow-clawed crayfish, Astacus leptodactylus , in the Islamic Republic of Iran. Crayfish from four sites in the Aras Dam Reservoir were sampled on 12 occasions during 2009. Abundance of B. kozarovi was modeled against water temperature, crayfish length, mass, and sex after controlling for temporal and spatial effects. The most parsimonious model indicates that B. kozarovi abundance was primarily related to water temperature but also increased linearly with host body length. We found that omitting water temperature dramatically decreased model performance while omitting host physical characteristics decreased model performance marginally. We recommend that ecologists consider both environmental and host physical characteristics when monitoring aquatic symbionts such as branchiobdellidans, as both types of factors will provide insight into community dynamics and guide future management strategies.