Specialized urban populations of birds: forms and mechanisms of the steadiness in urban environment. 2. Ecological and microevolutionary consequences of urban bird population steadiness. - V.S. Friedmann, G.S. Eremkin, N.Yu. Zakharova-Kubareva. - Berkut. 16 (1). 2007. - P. 7-51.
Ecological and evolutionary consequences of urban bird population steadiness developing during urbanization of “wild” species were investigated. It is shown that population system steadiness determines the diversity of adaptive “aberrations” in ecology, behaviour, life-history this species which are always observed in their urbanized populations. The diversity of “aberration” (and polymorphism by adaptive characters too) increases only in periods in which population is steady and their sustainability is in progress. The increasing of frequencies this “aberration” in urbanized bird population depends only on level the steadiness of species population in this city and not on ecological and behavioural plasticity of individuals or their possibilities of adaptation to urban environment. For example, all of these “aberrations” disappeared in period when urban population decreases through just this period they may to stopped population decreasing. The positive feedback between growth of urbanized population steadiness in same city and accelerating urbanization process for this species in next period were revealed. On account to impact this feedback on population level, urbanization proceed rapidly and directly, it is an autocatalytic process for all “wild” species which ensure the sustainability their population system in settling city. Some criteria of urban population steadiness were established (and opposite symptoms of population unsteady). There are: 1) absence “the limit of growth” urbanized birds populations can to exponentially increase their number in limited space the “archipelago” of urban habitats; 2) birds from sustainable urban populations did not leave the former nesting area after transformation or destroying their typical habitats, they try to stay on the breeding in this range and began to nest in non-typical habitats, build the nest with deviate methods and house it in non-typical places; 3) number dynamic of steady populations are independent from changes of some environment factors which are essential from this species (temperature, food abundance and so on), this dependence appear at once when it turned out that population system is unsteady; 4) birds in sustainable urbanized population will divide into two or more alternative life-strategies on the basis of population division on cohorts “moreover-settled” and “moreover-nomadic” individuals; 5) the dynamic equilibrium the frequencies of alternative strategies in urbanized population keep one’s balance in relatively stable urban environment but continually changed under impact of fluctuations urban environment or direct evolution of urban landscape. Successful urbanization process runs to splitting all population of this species in two parts (urban and “rural” or “native”) which are not communicating vessels. We established significant distinction between urbanization possibilities of near species (between ecological similar to) which distinguished from different type of organization the population systems. Causal connections between organization type of species population systems and urbanization potential were discussed as well as ecological and evolutionary consequences of urbanization. [Russian].
Key words: sinurbanization, population, metapopulation, strategy, urban gradient, preadaptation.
Address: V.S. Friedmann, Laboratory of ecology and nature conservation, biological faculty, Moscow university, Leninskiye gory, 1/12, 119992 Moscow, Russia; e-mail: wolf17@list.ru.