Abstracts

Evolution of Species and Ecosystems: Theoretical Analysis and Computer-Assisted Modeling

The development of population genetics is stimulated by accumulation of data on the dynamics of natural populations. The amphipod Eulimnogammarus cyaneus (Dyb.) is a very good object for studies in this field as its distribution area represents a narrow ribbon along the Lake Baikal surf about 2000 km long. Thus, E. cyaneus is represented in Lake Baikal by a system of one-dimensional populations studied before only at theoretical models or in laboratory experiments.

The research was done from Aprill, 1989 till August, 1990 on a stony beach near Bolshiye Koty settlement. Samples were taken two times per month from the frame of 0.1 m2. Abundance of E. cyaneus varies from 600 ind./m to 20000 ind./m , its biomass - from 5 g/m to 120 g/m . The reproduction period of E.cyaneus is ca. 9 months (March-November). Males and females ratio in the population is 1 : 1. E. cyaneus population divides into 4 cohorts, the life duration of which is 10 - 15 months. Two cohorts survive the winter as adults, two other ones – as juveniles. Each cohort is involved in the reproduction twice. Average embryonic stage is 225 degree-days, maturation stage (up to minimal sizes of mature specimens) takes 720 - 880 degree-days. Each cohort of juveniles derives from two parental ones, it provides population unity.

Scheme of cohorts reproduction

Population effective size and harmonic mean annual effective size (Altukhov, 1989) of E. cyaneus population was evaluated. It was taken into account while calculation that this E. cyaneus population gives 8 generations during the year, and migration processes were not taken into account. Harmonic mean annual effective size of E. cyaneus population on the territory studied is 140 ind./m . Taking into account that mean annual abundance of E. cyaneus on the territory investigated is 3000 ind./m , total population abundance exceed population effective size more than 20 times.

This work is being supported by RFBR grant No 01-04-97232.

Note. Abstracts are published in author's edition

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