Uticaj variranja sredinskih parametara na strukturu populacije obične krastače (Bufo bufo)

Abstract

Populacija obične krastače posmatrana je u sezoni razmnožavanja tokom pet uzastopnih godina. Odrasle jedinke su prebrojavane, merene i uzorkovane radi određivanja starosti (skeletohronologija). Glavni cilj je bio ispitati uticaj variranja odabranih meteoroloških parametara na fenologiju razmnožavanja populacije i promene brojnosti, efektivne veličine, odnosa polova, uzrasne strukture i kondicionog indeksa mase jedinki unutar adultnog dela populacije. Proverena je i povezanost između fekunditeta ženki, njihove starosti i veličine tela. Fekunditet je pretpostavljen poređenjem sa ranijim istraživanjima iste populacije. Utvrđen je trend ka povećanju prosečne dnevne temperature vazduha u periodu pre početka razmnožavanja, ali on nije uticao na promenu vremenske dinamike sezone parenja. Utvrđena je pozitivna korelacija između zima sa više padavina i broja jedinki koje su učestvovale u razmnožavanju. Efektivna veličina i uzrasna struktura populacije značajno su se menjali tokom godina, ali nezavisno od variranja meteoroloških parametara. Utvrđena je slaba negativna korelacija između toplijih zima i vrednosti kondicionog indeksa jedinki, koji je takođe značajno varirao tokom godina. Adultnih mužjaka je bilo znatno više od adultnih ženki. Ženke su bile veće od mužjaka. Indeks polnog dimorfizma u veličini tela je varirao između godina. Asortativno ukrštanje nije potvrđeno. Mužjaci u ampleksusu su bili krupniji od mužjaka bez ženki, ali nisu imali veći kondicioni indeks mase. Ženke veće mase tela imale su veći pretpostavljeni fekunditet, ali se on nije značajno menjao sa starošću. Utvrđene su značajne fluktuacije strukture i dinamike analizirane populacije, ali je potrebno više godina posmatranja da bi se utvrdio mogući uticaj variranja meteoroloških parametara.

One population of common toads was monitored on the breeding grounds for five consecutive years (2011–2015). Individuals were counted, measured and samples of hind leg toe phalange were taken for age assessment by sкeletochronology. The main goal was to analyse the effects of some weather parameters on reproductive phenology of this population. Change of effective and census population size, sex ratio, age structure and body mass condition index (BMCI), as well as relations among female fecundity, age, and body size, were also analysed in adult part of this population over time. Female fecundity was calculated regarding body mass, derived by comparison with earlier study. The trend was found toward increase of average daily air temperature in period before start of the breeding season, but it didn’t have impact on change in temporal dynamics of the breeding season. Positive correlation was found between winters with more precipitation and reproductive population size. Effective population size and age structure significantly varied along years, but independently from variation of weather parameters. Weak negative correlation was found between warmer winters and BMCI. BMCI also varied significantly along years. Females were larger than males. Index of sexual dimorphism in body size varied along years. Assortative mating was not confirmed. Males recorded in amplexus were bigger than solitary males, but generally didn’t differ in BMCI. Heavier females also had higher projected fecundity, and it didn’t change with age. Significant fluctuations of structure and dynamics were recorded in this population, but more years of monitoring are required to check possible impact of variation of weather parameters.