Meristic and Morphological Differentiation of Orestias Species (Teleostei; Cyprinodontiformes) from the Southern Altiplano
Total Page：16
File Type：pdf, Size：1020Kb
Environ Biol Fish (2020) 103:939–951 https://doi.org/10.1007/s10641-020-00995-4 Meristic and morphological differentiation of Orestias species (Teleostei; Cyprinodontiformes) from the southern Altiplano Sergio Scott & Pablo Rojas & Irma Vila Received: 5 March 2020 /Accepted: 14 June 2020 / Published online: 22 June 2020 # Springer Nature B.V. 2020 Abstract Orestias is an endemic fish genus of lacustrine Keywords Andean high plateau . Freshwater fish . and lotic systems distributed on the Andes highland region Morphology (Altiplano) of Peru, Bolivia and Chile (9°S to 22°S). Based on morphological characters, taxonomic studies have recognized seven species on the Chilean western Introduction southern Altiplano region (17°S - 22°S). The current geographical distribution of Orestias would be associated Traditionally, taxonomic studies for the identification of with historical vicariant events and fluctuations in water species members have been carried out using morpho- levels since the Pleistocene. In this context, this group logical and meristic characteristics (Cadrin 2000), where arises as an interesting model to assess Orestias morpho- specimens or their populations may present overlaps logical adaptations in Altiplano systems. Morphological when characters are invariant. (Swain and Foote 1999; and meristic analyses were performed on ten populations Murta 2000). When fish are exposed to different envi- of Orestias in the southern Altiplano. The results showed ronmental conditions, they can adjust their morphology significant differences among populations. The meristic and evolve with adaptations that allow them to survive and morphometric characters were related to physical and the new conditions (Webb 1984). The environment is a chemical properties of their habitat. We considered the powerful force that models the morphology of organ- systematic validation of the Orestias species and the pos- isms during their ontogeny (Costa and Cataudella sible future determination of new species of the popula- 2007). Hence, morphology is not only a result of their tions of O.cf.agassii of Huasco saltpan, Isluga River and genetics but also of their environment and behavior Chuviri wetland, which should be tested with trophic, (Guill et al. 2003). genetic and karyotype analyses. Ecosystem dynamism and geographic isolation may enable specimens to experience a wide range of ecological S. Scott : P. Rojas : I. Vila (*) conditions, leading to morphological differences and local Department of Ecological Sciences, University of Chile, Las adaptations (Schluter 1993, 1996, 2000; Losos et al. 1998; Palmeras, 3425 Santiago, Chile Kocher 2004; Maldonado et al. 2009). For this reason, it is e-mail: [email protected] suggested that natural selection may lead species into S. Scott occupying similar ecological niches with certain morpho- Applied Research Center of Chile, CIACHI, Badajoz 100, logical and meristic characteristics, in response to equiva- Santiago, Chile lent selective pressures (Wainwright 1991, 1996; Hugueny S. Scott and Pouilly 1999; Cardin and Friedland 1999; Pouilly et al. Educational and Science Foundation, Castillo Urizar, 2003; Poulet et al. 2005;Merona2005). The quantification 2949 Santiago, Chile of specific characteristics of a specimen or group of 940 Environ Biol Fish (2020) 103:939–951 specimens may demonstrate the degree of speciation in- The objective of this study has been to analyze the duced by biotic and abiotic conditions, contributing to the morphological and meristic differences between the definition of different groups of species (Bailey 1997; species of Orestias of the southern Altiplano. We hy- Nacua et al. 2010). pothesized differences among the populations of To understand the morphological responses of organ- Orestias, principally due to historical isolation and par- isms to environmental conditions, patterns of morpho- ticular environmental conditions of each ecosystem of logical variation have been compared with patterns of the southern Altiplano. For this, a higher number of variation in ecological characteristics (Norton et al. individuals have been considered for the morphological 1995; Maldonado et al. 2009). These analyses have and meristic analyses, incorporating adults of different helped to determine whether there is phenotypic diver- sizes and considering all the species described for this gence among different species or populations of the zone, as well as new populations under study. same species, and which could have an impact on them, shedding light on the interaction that species have had with their environment since their separation from their Material and methods dispersal center. A habitat freshwater heterogeneity (lo- tic and lentic) could potentially create a spatial variation The study included 258 Orestias specimens collected or facilitate morphological plasticity (Franssen 2011). between 2013 and 2016 (Table 1) in 10 different sys- For example, the lotic environments select a body fusi- tems of the southern Altiplano (Fig. 1). The fish were form shape by reducing the resistance of the water captured using hand nets, as well as electrofishing stream, obtaining lower energy costs (Webb 1984; (SAMUS -725) at deeper places. Fish were fixed with Langerhans and Reznick 2010;Fosteretal.2015). 95% alcohol after being euthanized with Tricaine The genus Orestias described in the southern Alti- methanesulfonate (MS222). Posteriorly, at the laborato- plano (17° to 22° S) inhabits aquatic systems as diverse ry, the alcohol was removed and fish were fixed with as high lakes, rivers, saltpans and wetlands (locally new 95% alcohol. Finally, the specimens were included called bofedales) of the Andes. Most systematic studies to the collection of the Limnology Laboratory of the have emphasized the use of meristic and morphological University of Chile (Table 1). characters for Orestias species characterization. Up to The species included in this study were now, species descriptions have mainly considered rela- O. parinacotensis (Arratia 1982) from Parinacota wetland tionships of body proportions, number and distribution (18°12’ S; 69°16’ W), O. laucaensis (Arratia 1982) from of scales, fin rays and gills characteristics (Arratia 1982; Lauca River (18°11’ S; 68°16’ W) and Cotacotani lake Lauzanne 1982; Parenti 1984a; Costa 1997;Vilaetal. (18°12’ S; 69°14’ W), O. chungarensis (Vila and Pinto 2011, 2013), yet lacking an analysis which would cor- 1986) of Lake Chungará (18°15’ S; 69°07’ W), relate the set of characters with the environmental var- O. ascotanensis (Parenti 1984a)ofAscotánsaltpan(21° iations where the species live. S; 68° W), O. piacotensis (Vila 2006)ofPiacotalake Seven Orestias species have been described for the (18°12’ S; 69°158’ W); O.cf.agassii (Valenciennes, southern Altiplano (Fig. 1); Orestias piacotensis (Vila 1846) of Huasco saltpan (20°16’ S; 68°41’ W) O.cf. 2006), O. laucaensis (Arratia 1982), O. parinacotensis agassii of Isluga River (19°01’ S; 68°42’ W), O.cf.agassii (Arratia 1982), O. chungarensis (Vila and Pinto 1986), of Chuviri wetland (18°10’ S; 69°20’ W) and O. gloriae O.cf.agassii (Mann, 1954), O. gloriae (Vilaetal.2011) (Vila et al. 2011) of Carcote saltpan (21°17’ S; 68°19’ W). and O. ascotanensis (Parenti, 1984). The validity of the The descriptions of Arratia (1982); Parenti (1984a); Vila species described for the agassii complex of the south- and Pinto (1986), Vila (2006) and Vila et al. (2011)were ern Altiplano has been questioned by Villwock and used to determine the species. Sienknecht (1995, 1996), postulating that they represent For the morphological analyses of the species studied, ontogenetic stages and that they could also represent the following measurements were standardized for each geographical variations of the same species. The likely specimen size: eye diameter, head length, pre dorsal length, source of discrepancy is that the original descriptions standard length, total length, pre orbital length, caudal were based on the analyses of a limited number of peduncle length, pre anal length, body height, caudal specimens of the same ontogenetic stage (Villwock peduncle height, and head height (Fig. 2). For the meristic and Sienknecht 1995, 1996). analyses, the same specimens were used, counting the Environ Biol Fish (2020) 103:939–951 941 Fig. 1 Distribution map of the Orestias species used in this study number of scales of the lateral line, the number of rays of into fluvial O. laucaensis,andO.cf.agassii of Isluga; O. the dorsal, anal, pectoral and caudal fins cf. agassii from Huasco, O. ascotanensis and O. gloriae in (Appendix Table 5). Data were analyzed by a MANOVA saltpans; O. chungarensis O. piacotensis as lacustrines; (Multivariate variance analysis) using all morphometric O. laucaensis of Cotacotani, O. parinacotensis and O.cf. measurements, grouping specimens by sampled localities, agassii of Chuviri from wetlands. A Principal Component and grouped also by type of environment classifying them analysis (PCA) and Linear discriminant analysis (LDA) Table 1 Locality of the populations of Orestias collected Populations Locality Latitude/ Longitude N° Ind O. parinacotensis Parinacota wetland 18°12’S/ 69°16’W29 O. laucaensis Lauca river 18°22’S/ 69°20’W27 O. laucaensis Cotacotani lake 18°12’S/ 69°14’W28 O. chungarensis Chungara Lake 18°15’S/ 69°10’W16 O. ascotanensis Ascotan salt pan 21°29’S/ 68°15’W22 O. gloriae Carcote salt pan 21°16’S/ 68°19’W28 O. piacotensis Piacota lake 18°12’S/69°16’W27 O.cf.agassii Isluga river 19°15’S/68°42’W28 O.cf.agassii