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FOLIA Folia Malacol. 24(3): 111–177 MALACOLOGICA ISSN 1506-7629 The Association of Polish Malacologists Faculty of Biology, Adam Mickiewicz University Bogucki Wydawnictwo Naukowe Poznań, September 2016 http://dx.doi.org/10.12657/folmal.024.008 PATTERNS OF SPATIO-TEMPORAL VARIATION IN LAND SNAILS: A MULTI-SCALE APPROACH SERGEY S. KRAMARENKO Mykolaiv National Agrarian University, Paryzka Komuna St. 9, Mykolaiv, 54020, Ukraine (e-mail: [email protected]) ABSTRACT: Mechanisms which govern patterns of intra-specific vatiation in land snails were traced within areas of different size, using Brephulopsis cylindrica (Menke), Chondrula tridens (O. F. Müller), Xeropicta derbentina (Krynicki), X. krynickii (Krynicki), Cepaea vindobonensis (Férussac) and Helix albescens Rossmässler as examples. Morphometric shell variation, colour and banding pattern polymorphism as well as genetic polymorphism (allozymes and RAPD markers) were studied. The results and literature data were analysed in an attempt to link patterns to processes, with the following conclusions. Formation of patterns of intra- specific variation (initial processes of microevolution) takes different course at three different spatial scales. At micro-geographical scale the dominant role is played by eco-demographic characteristics of the species in the context of fluctuating environmental factors. At meso-geographical scale a special part is played by stochastic population-genetic processes. At macro-geographical scale more or less distinct clinal patterns are associated with basic macroclimatic indices, while the stochastic processes tend to lose importance. The basic factors of microevolutionary process which act at different spatial scales result from processes which progress over different lengths of time: micro-geographical variation patterns reflect processes which are in progress at the moment; meso-geographical variation is to a larger extent determined by processes which occurred in historic past; macro-geographical variation reflects processes which coincided with formation of the respective landscapes or climate zones. KEY WORDS: intra-specific vatiation, Brephulopsis cylindrica, Chondrula tridens, Xeropicta, Cepaea vindobonensis, Helix albescens, spatial scale, microevolution, multi-scale approach, morphometric variation, colour polymorphism, genetic polymorphism INTRODUCTION The relatively easy collecting and field observa- tanical history of the habitats. It is however difficult tions, as well as laboratory experiments, have made to discern between the results of microevolutionary land snail variation a popular object of studies. Land processes which are in progress at the moment and snails display a very easily observable intra- and in- those which have occurred in the recent past. One ter-population variation of both qualitative and quan- of the most reliable ways of solving the problem is titative characters of their shells and soft parts, and comparison of spatial patterns of variation of differ- small mobility; their mostly bi-parental reproduction ent kinds (anatomical-morphological, biochemical, is combined with hermaphroditic reproductive sys- molecular etc.), which are to different extent suscep- tem. In their case it is relatively easy to collect large tible to various genetic and demographic processes samples, since even after death the shells remain, (MOUSSEAU et al. 2000, SCHOVILLE et al. 2012). and to keep and breed them in laboratory (CLARKE et The concept of distribution pattern, either of al. 1978, CAIN 1983, THOMAZ et al. 1996). taxa or of genotypes, is necessarily associated with Variation patterns depend not only on genetic the concept of scale. Moreover, it is also necessary factors (mutations, gene flow, drift and natural se- to define the scale in order to achieve an adequate lection), but also on the climatic, faunal and geobo- estimate of variation (LEVIN 1992, CONOVER et al. Folia Malacologica is funded by the Ministry of Science and Higher Education, Republic of Poland under agreement no. 646/P-DUN/2016 allocated to the activities of disseminating science 112 Sergey S. Kramarenko 2006, CUSHMAN & LANDGUTH 2010, SCHOVILLE et al. genetic variation at intra- and inter-population levels, 2012). Due to the fact that evolutionary forces act at which obviously results from the wide application of different (and species-specific) scales, a multi-scale the “hierarchical AMOVA” method (EXCOFFIER et al. approach to the analysis of the populations’ genetic 1992) with the use of corresponding software. There and phenotypic structure is necessary. is also a deficit of studies which at the same time Two scales are most often considered during consider expressions of various kinds of intra-spe- sampling and subsequent analysis of the resulting cific variation (genetic and morphometric, or genetic data: micro-geographical (fine-scale, small-scale; and variation in shell colour and banding pattern) in SELANDER & KAUFMAN 1975, COLGAN 1981, BAUR land snails at intra- and inter-population levels. 1988, TATARENKOV & JOHANNESSON 1994, FLETCHER On the other hand, processes which take place at 1995) and macro-geographical (large-scale; GROUE various spatial scales should be considered through 1980, DE WOLF et al. 1988, 1998, DÄUMER et al. different lengths of time, hence the resulting pat- 2012). However, no sharp dividing line between the terns of intra-specific variation should be regarded as two has yet been proposed, which leads to various spatio-temporal. At present analyses of chronologi- authors using completely different scales, even when cal variation of shell size and form in land snails in- dealing with the same group of animals. clude periods of time ranging from one year (COOK & In the analysed literature (around 150 papers), O’DONALD 1971, KRAMARENKO 2006) to a few tens dealing with numerous kinds of intra-specific vari- of years (PETTITT 1977, COOK & PETTITT 1979, CAIN ation in land snails (morphometric variation, colour & COOK 1989). and banding pattern polymorphism or genetic poly- Analyses of chronological patterns of variation in moprhism), I found different scales adopted by dif- land snail populations with regard to shell banding ferent authors in their sampling procedures. There polymorphism also testify to the existence of various is a considerable prevalence of research on variation scales; the patterns differ significantly depending on of shell size and form at macro-geographical scale on the scale. Over short periods (10–15 years) formation the one hand, and a deficit of studies dealing with of random patterns is observed, and changes in morph formation of intra-population variation patterns at frequencies are unpredictable (WOLDA 1969, COWIE micro- and meso-geographical scales on the other. 1992, OżgO & BOgucki 2011). In long-term analy- Moreover, the proportion of studies which use ses (40–60 years) significant decrease or increase in two or more scales of spatial organisation of sam- the frequencies of some morphs occurs (CAMERON pling and data analysis at the same time is very small. & POKRYSZKO 2008, SILVERTOWN et al. 2011, OżgO Likewise, the percentage of papers using hierarchical & SCHILTHUIZEN 2012, CAMERON et al. 2013). Thus (nested) method of data collecting and processing to chronological patterns of variation of terrestrial snails estimate the components of variation at various lev- also display a scale-dependent variation. els of the scales applied is very small. Overall, not The main objective of my study was analysis more than 10% of the published papers apply both of mechanisms of formation of spatio-temporal multi-scale approach to sampling and hierarchical patterns of intra-specific (intra- and inter -population) procedures to estimate the components of variation, morpho metric and genetic variation of land snails at which are defined by different scales of investigation. various spatial and temporal scales. Exceptions are publications dealing with analysis of MATERIAL AND METHODS MORPHOMETRIC ANALYSIS ments were taken with slide calliper (accuracy 0.05 mm) according to the commonly adopted method Morphometric analysis used four species which (SVERLOVA et al. 2006). are widespread in Ukraine and adjacent countries – The main object of the study was morphometric Chondrula tridens (O. F. Müller, 1774), Brephulopsis cy shell variation within and between populations of the lindrica (Menke, 1828), Cepaea vindobonensis (Férussac, selected snail species. The analysis was based on the 1821) and Helix albescens Rossmässler, 1839. Two estimation of variance components of the dependent shell parameters were measured for each of them: variable (morphometric character), which were ob- for B. cylindrica and Ch. tridens shell height (HS) and tained using the general linear model (GLM) (SCHEFFÉ greatest shell width (WS), and two indices of shell 1999). Besides the estimate of variance components of proportion were calculated: FS1 = HS/WS and FS2 = the dependent variable (in order to compare variation lnHS/lnWS. In the case of the two helicids shell di- of different characters), the estimates of variance com- ameter (DS) and shell height (HS) were used, as well ponents were transformed into relative values (MST), as proportion index (FS = HS/DS). All the measure- which expressed the proportional effect of the inde- Spatio-temporal variation in land snails 113 pendent variable on the variation of the dependent Calculations were done with SAM v. 4.0 (RANGEL et variable (fixed effects model; KRAMARENKO 2009a). al. 2010), PAST v. 2.14