The 7 traditional classes of Vertebrates (3 classes of Fish, Birds, Mammals, Reptiles and Amphibians) encompass around 64 000 species and are by far the best known animal group from a demographic point of view. After having briefly recalled the reasons for the abundance and quality of the demographic information available on Vertebrates, I will review this information, covering the following salient features:
- Most vertebrates have a discrete life cycle, with a seasonal or nearly seasonal sexual reproduction, and primarily age-dependent variation in demographic traits.
- The demographic differences among Vertebrates can naturally be ordered on a "slow- fast gradient" best measured by generation time. From short-lived rodents to cetaceans or sea turtles, the change in generation time is at least 300-fold.
- This variation is strongly linked in an allometric fashion to body weight within groups of species sharing a common general body "ground design", with major differences among groups (e.g., Chiroptera - Bats- vs Rodents; Anseriforms - Ducks, Geese and Swans- vs Procellariiforms (Albatross and related seabirds).
- In relation with the allocation of energetic resources, maximum population growth rate is inversely related to generation time, the longest lived species having thus the smallest maximum growth rate, and as a consequence, the smallest resilience to extra sources of mortality. Together with behavioral and physio-energetic features, this demographic sensitivity induces a genuine "malediction of long-lived species" in face of human activities, with many different illustrations, including the overfishing of stocks of large fish. It is particularly striking that the 5 species of Hominids beside Man are classified as "endangered" by the International Union for Conservation of Nature (IUCN). Over the last 5 centuries, more than one species of Vertebrate got extinct each year.
- Besides the dominant role of age, demographic heterogeneity within age classes has been shown as to be present in a growing number of Vertebrate species and may be quite general.
- Dispersal patterns are less widely known, but clearly show a prominent role of dispersal between birth and first reproduction, with a stronger dispersion of males or females, depending mostly on the class of Vertebrates considered.
I discuss implications of these demographic characteristics of Vertebrate in a changing world, in particular in relation with climate change and the fragmentation of habitats.