Inter - and intraspecific phenotypic variation in co-occurring invasive and introduced cyprinid fish species.

A species introduced outside of its native range will likely encounter unusual abiotic and biotic conditions,and may exhibit phenotypic traits that may facilitate survival and persistance. Phenotypic plasticity drives non-native species' development of adaptive traits in the new environment, increases their fitness, and as a result, contributes to invasion success. In this study, we examined inter and intraspecific phenotypic variation (body size and shape) for an invasive (Carassius gibelio) and introduced (Cyprinus carpio) cyprinid fish species (Teleostei: Cyprinidae) in the Düden Stream, Turkey, which is a small-scale river system. We hypothesized that interspecific phenotypic variation correlates with fish-specific variables and river site. We further hypothesized that these two species may exhibit similar phenotypic variation patterns between populations. The MANCOVA revealed that species-specific traits, river site, had significant effects on body shape variation and size along the stream. The differences in the shape of the head, the central portion of the body, and fins in both species most probably reflected differences in the swimming and feeding of the fish, possibly to avoid interspecies competition. The intraspecific phenotypic variation observed in both species may indicate rapid local adaptation, triggered by multiple founding event, or/and phenotypic plasticity.

Morphological and functional trait divergence in endemic fish populations along the small-scale karstic stream.

BACKGROUND: Organisms with broad distribution ranges, such as fish, often exhibit local ecological specializations based on their utilization of food and habitat. Populations of species that live in different habitat types (lotic vs. lentic) show morphological variations. However, the phenotypic differences of endemic fish populations in a small karst river basin under anthropogenic pressure are still not fully understood. In this study, the functional traits and morphological variations of the populations of endemic Pseudophoxinus antalyae Bogutskaya, 1992, in the Düden Stream basin, which is subjected to various anthropogenic disturbances and habitat types in southwestern Anatolia of Türkiye, were examined using linear measurements and geometric morphometric analysis. RESULTS: Differences have been identified in functional traits, particularly those related to food acquisition between populations. Results of both univariate and multivariate analyses revealed significant differences in body shape and size among populations living at sites along the stream with different habitat and environmental characteristics. CONCLUSIONS: The reason for these differences determined in the morphology and traits of the populations may depend on habitat types, ecological, or environmental, and obstruction of gene flow. More detailed studies are needed to explain the mechanisms (genetic and ecological) that cause these differences.

Systematics of the genus Heterolaophonte (Crustacea, Copepoda, Harpacticoida), with redescription of H. uncinata and H. curvata.

Both sexes of Heterolaophonte uncinata (Cherniavski, 1868) and H. curvata (Douwe, 1929) are redescribed based on newly collected material from the Black Sea and Mediterranean coasts of Turkey in view of the fact that there has been no detailed redescription since their original descriptions. Neotypes are also designated for both species. Detailed comparisons of the characters displayed among Heterolaophonte Lang, 1948 species reveal that the genus cannot be defined by any unique apomorphy. We propose that the structure of the male appendages, especially the swimming legs, can provide a considerable number of significant characters that are valuable both for taxonomic identification and phylogenetic inferences. In addition, several mistakes leading to a great confusion in the accurate interpretation of the relationships among species within Heterolaophonte are discovered in earlier species descriptions. Therefore, H. rottenburgi (T. Scott, 1912), H. exigua (T. Scott, 1912), H. australis (T. Scott, 1912), and H. insignis (T. Scott, 1914) are removed from the genus and placed as incertae sedis in Laophontidae. We also conclude that H. phycobates (Monard, 1935), H. pygmaea (T. Scott, 1893), H. tupitskyi Chislenko, 1976, and H. curvata micarthros Marcus & Por, 1960, which still need further taxonomic investigation, have doubtful identity within the genus, and we place them as species inquirendae.