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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
Cohort |
Birth month |
Parental cohorts |
I |
6 |
II,III |
II |
7-8 |
III,IV |
III |
9 |
I,IV |
IV |
10-11 |
I,II |
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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