TAILIEUCHUNG - From Individuals to Ecosystems 4th Edition - Chapter 6

Chapter 6 Dispersal, Dormancy and Metapopulations Introduction All organisms in nature are where we find them because they have moved there. This is true for even the most apparently sedentary of organisms, such as oysters and redwood trees. | Chapter 6 Dispersal Dormancy and Metapopulations the meanings of dispersal and migration Introduction All organisms in nature are where we find them because they have moved there. This is true for even the most apparently sedentary of organisms such as oysters and redwood trees. Their movements range from the passive transport that affects many plant seeds to the apparently purposeful actions of many mobile animals. Dispersal and migration are used to describe aspects of the movement of organisms. The terms are defined for groups of organisms although it is of course the individual that moves. Dispersal is most often taken to mean a spreading of individuals away from others and is therefore an appropriate description for several kinds of movements i of plant seeds or starfish larvae away from each other and their parents ii of voles from one area of grassland to another usually leaving residents behind and being counterbalanced by the dispersal of other voles in the other direction and iii of land birds amongst an archipelago of islands or aphids amongst a mixed stand of plants in the search for a suitable habitat. Migration is most often taken to mean the mass directional movements of large numbers of a species from one location to another. The term therefore applies to classic migrations the movements of locust swarms the intercontinental journeys of birds but also to less obvious examples like the to and fro movements of shore animals following the tidal cycle. Whatever the precise details of dispersal in particular cases it will be useful in this chapter to divide the process into three phases starting moving and stopping South et al. 2002 or put another way emigration transfer and immigration Ims Yoccoz 1997 . The three phases differ and the questions we ask about them differ both from a behavioral point of view what triggers the initiation and cessation of movement etc. and from a demographic point of view the distinction between loss and gain of .

TỪ KHÓA LIÊN QUAN
Đã phát hiện trình chặn quảng cáo AdBlock
Trang web này phụ thuộc vào doanh thu từ số lần hiển thị quảng cáo để tồn tại. Vui lòng tắt trình chặn quảng cáo của bạn hoặc tạm dừng tính năng chặn quảng cáo cho trang web này.