Species-area Relationship of Herpetofaunas in West Indies

Species- ara Relationship of Herpetofaunas in western IndiesDe Gao1. Introduction1.1. Biodiversity and crisis on western IndiesOceanic islands, due to their distinguishable geographical isolation, differ distinctly from terrestrialecosystem, offer great opportunities for species conservation, and ar regarded as the naturallaboratory for the study of biogeography and evolutionary ecology (Adsersen, 1995 Crawfordand Stuessy, 1997 Ricklefs and Bermingham, 2008). Island home ground hetero elementity and the geneflow barrier between the island and its neighboring islands or land are the rough important drivingforces leading to brand-new species differentiation and formation (Cherry et al. 2002). The colonizedspecies from continents or nearby islands are and so subjected to unique evolutionary processes,for example, geographic isolation, character displacement, and adaptive radiation. Theaccumulated mutations little by little and ultimately make colonized species into new indige nousspecies that are genetic all(prenominal)y different from the original one. One of the most(prenominal) distinctive features ofthe biota on oceanic islands is the large number of reverseemics occurring in small areas (Francisco-Ortega et al. 2000).West Indies was identify as a biodiversity hotspot by Myers et al. (2000). A significant constituent of the Earths known terrestrial biota is distributed on islands of the West Indies,many of these species are endemic to the persona, to individual islands, and even to isolated areas inwardly some islands (Hedges, 2001). But a large majority of the vast abstruse of islands in WestIndies is changing rapidly, resulting in dramatic alterations of home grounds, and nearly all of them aremediated by human activities (Powell and Henderson, 2012). Small population size, gene drift,isolated gene flow, and the complexity of island environment develop already make the endemicherpetofaunal species easy to be endangered or extinct, human anxi etys doubtlessly worsenthe situation. Therefore, detailed conservation concerns in West Indian region are change magnitudelyimportant and required.1.2. Species-area relationship (SAR)The species-area relationship is one of the most fundamental patterns in macroecology and animportant tool in assessing species diversity, quenching rate and species hotspots (Tjrve, 2009).According to the equilibrium theory (MacArthur and Wilson, 1967), the relationship betweenimmigration and the extinction of species to island depends on the island size and its distance tomainland. MacArthur-Wilsons theory provided impetus for numerous studies on species-arearelationships (SARs) that have provided biological interpretations for several taxa and havesuggested factors and mechanisms that can reconcile species richness (Simaiakis et al. 2012).And the theory has an enormous influence on perspectives of species conservation and spiritreserves design.The main objective of this chapter is to discuss SAR s for herpetofaunas in West Indies regions,with the aim of discover which factors may determine their distribution over the full range ofisland sizes. We choose to fit some candidate toughies including the power illustration and somesigmoid models to see whether a J- counterfeitd part comprises at the get end of the curve. Small-island raise (SIE) holds that, on islands smaller than a certain critical minimum area, one cannotobserve an increase in species number with increasing area (Simaiakis et al. 2012). We choose tofit candidate models including the power model and some sigmoid models to see whether a J-shaped part exists at the lower end of the curve. If the best fitted model has a sigmoid shape, a J-shaped part testament exist at the lower end, and then we accept SIE. If the best fitted model has aconvex shape, a J-shaped part lead not exist at the lower end, and then we deny SIE. There are exchangeablely other reasons why it is so important to know the shape of speci es-area curve. base on thecurve shape, we could estimate total species diversity from limited numbers game of samples, orestimate species extinction as a result of habitat loss and fragmentation (Tjrve, 2003).Candidate species-area models are proposed from two bloods. The first source is species-arealiterature which has traditionally fit data with power or exponential function models, the second sourceinvolves a broader search of the literature for models that increased monotonically to anasymptote (Flather, 1996).Although the shape of the curve has been extensively debated over the years, power andexponential curves are the most commonly applied and best known ones, lately, an increasingnumber of authors have argued some SARs are perhaps best represented by functions that aresigmoid in arithmetic space and on that point are also a number of recent studies where sigmoid modelshave been fitted to empirical data (Tjrve, 2003). Some sigmoid models behave similar withothers, for ins tance, the Extreme order function behaves quite similar to the Logistic andGompertz models The Cumulative beta-P distribution behaves similarly to the Weibulldistribution (Tjrve, 2003).2. AimsIn this study, we are trying to solve 3 questions disbelief 1 What is the species-area relationship (SAR) for herpetofaunas in West Indies? Is theSAR same for native and incursive species? And is it the same among each animal groupclassification under amphibious and reptile?Question 2 Due to humans help, invasive species are supposed to have a higher dispersal competency as compared to the native. So, in the running(a) form of the power model (LogS/LogA) is therea higher z-value for the invasive species than the native species?Question 3 What geographic factors may determine species richness over the whole range ofisland sizes? be these factors also applicable to other group of islands that located in similarlatitude areas to determine their species richness?3. Material and MethodsData on species occurrences educate from Powell and Henderson (2012). Multiple basemaps inArcMap 10 and ArcGlobe 10 will be use to digitize islands map. We use different homes todigitize islands with various areas. Fractal psychoanalysis will be used to estimate the perimeters at auniform scale (Farina, 2007). For comparisons of the fit of different models, the Akaikesinformation criterion (AIC) was applied (Burnham and Anderson, 2002). ride selectionanalyses will run using mmSAR package (Guilhaumon et al. 2010) for the R statistical andprogramming environment (R Development Core Team, 2011).Aim 1 mildew selectionwe use the 8 most general models composed in mmSAR package (Guilhaumon et al. 2010) tofit the data, which include 5 convex models (Power, Exponential, Negative exponential, Monod, demythologized function) and 3 sigmoid models (Logistic, Lomolino, Cumulative Weibull).Aim 2 LogS/LogA linear lapsingWe analyze the linear function of the LogS/LogA and compare parameter values wit h vertebratesfrom globular oceanic islands (Triantis et al. 2012).Aim 3 Find out the geographic factors relate species richness/StepsInitially selected variables areX1 Distance to mainlandX2 Latitude of island centroidX3 Longitude of island centroidX4 Island none within 0.1kmX5 Island No. within 0.1-1kmX6 Island No. within 1-5kmX7 Island No. within 5-10kmX8 Islands cranial orbit within 0.1kmX9 Islands Area within 0.1-1kmX10 Islands Area within 1-5kmX11 Islands Area within 5-10kmX12 Area of the islandX13 Perimeter of the islandX14 Perimeter/AreaX15 fortune of botanyX16 Percentage of human areaX17 Rivers within the islandX18 Invasive spp. within the islandX19 Percentage of invasive spp.X1 and X3 are used to probe species dispersal from mainland X2 is used to experiment thenearness to equator X4, X5, X6, X7 are used to examine stepping stones in each handbuild circle X8,X9, X10, X11 are used to examine total area of stepping stones in each loop circle X12 is used to examine a rea effect X13 and X14 are used to examine shape (irregularity) of island X15,X17 are used to examine habitat quality X16, X18, X19 are used to examine human disturbanceand invasive species.Principal Component Analysis and Hierarchical Partitioning Analysis will be made based on theresiduals distribution of LogS/LogA linear regression to examine which geographic factors arethe significant contributions of species richness in West Indies.