Is body size a life history trait?
Some life history traits include the size of an animal at birth (or at hatching), the age and size at which an animal reaches reproductive maturity, how it reproduces (oviparous or viviparous), how often it can reproduce (semelparous or iteroparous), the length of time it is reproductively active, the number and size …
Are humans Semelparous or Iteroparous?
The term iteroparity comes from the Latin itero, to repeat, and pario, to beget. An example of an iteroparous organism is a human—humans are biologically capable of having offspring many times over the course of their lives. Iteroparous vertebrates include all birds, most reptiles, virtually all mammals, and most fish.
Are turtles Semelparous?
Two of the most successful types of reproductive styles are called iteroparity and semelparity. Sea turtles are an example of iteroparity.
Why are humans Iteroparous?
That is, according to these models, humans are an iteroparous species because the benefits of devoting reproductive efforts to multiple offspring outweigh the risk of infantile mortality.
What is an R strategist and K strategist?
The terms r-selection and K-selection are used by ecologists to describe the growth and reproduction strategies of organisms. r-selected species have a high growth rate but low survivability (“cheap” offspring) K-selected species have a low growth rate but high survivability (“expensive” offspring)
Are humans R or K strategists?
Both across and within species, r and K strategists differ in a suite of correlated characteristics. Humans are the most K of all. K’s supposedly have a longer gestation period, a higher birthweight, a more delayed sexual maturation, a lower sex drive, and a longer life.
What does R stand for in r-selected species?
A whale tends for a single calf. r-selection: On one extreme are the species that are highly r-selected. r is for reproduction. Such a species puts only a small investment of resources into each offspring, but produces many such low effort babies.
What is r at carrying capacity?
In the equations describing growth of populations of organisms, r represents the slope of the line representing exponential growth. The letter K represents the carrying capacity of a habitat for members of a given sort of organism.
Are dogs K strategists?
Indeed, one can think of a given organism as an “r-strategist” or a “K-strategist” only relative to some other organism; thus statements about r and K selection are invariably comparative. Cats and dogs are r-selected compared to humans, but K-selected compared to mice and rats.
Are cats K strategists?
Animals such as fish and frogs that lay hundreds of eggs at a time are R-strategists, animals such as humans, puffins and the majority of other organisms are K-strategists. The image shown shows a cat, an example of a organisms that produces few long living organisms.
What does R stand for in ecology?
The first variable is r (the intrinsic rate of natural increase in population size, density independent) and the second variable is K (the carrying capacity of a population, density dependent).
What is r rule?
The R* rule (also called the resource-ratio hypothesis) is a hypothesis in community ecology that attempts to predict which species will become dominant as the result of competition for resources. A large number of experimental studies have attempted to verify the predictions of the R* rule.
What is the difference between λ and R?
One way to think about the relationship between r and λ is that λ is the contribution of an individual to the total population size, whereas r is the contribution of an individual to the rate of change in population size.
What happens to the population from 110 years to 140 years?
Between 110 years and 140 years the white pine population decreased quickly and then came back a little. Constant- when you look at a population graph and number of organisms stays almost the same. Why did our number of rabbits become constant? Because the environment reached its carrying capacity.
Does R change based on time or population size?
No, r is a constant, so it will not change with time or population size. (In the simulator, for example, you use only one value for r when making a plot.)
What causes Allee effect?
The most commonly observed mechanism is mate limitation, which causes Allee effects in both animals and plants (in the form of pollen limitation). Positive density dependence in survivorship due to either cooperative defense or predator satiation is also found across taxonomic groups.
What is a strong Allee effect?
The strong Allee effect is a demographic Allee effect with a critical population size or density. Meanwhile, a population exhibiting a strong Allee effect will have a critical population size or density under which the population growth rate becomes negative.
Is Allee effect good or bad?
Allee effects, or positive density-dependence, are phenomena that lead to positive relationships between population density and individual fitness and, therefore, can play an important role in driving small animal populations to extinction [1].
What causes outbreeding depression?
Evidence for outbreeding depression comes primarily from organisms with extremely limited dispersal, such as some plants, copepods, and scale insects, or from crosses between individuals from vastly different geographic sources, or with significant chromosomal differences.
What is the difference between inbreeding depression and outbreeding depression?
Inbreeding refers to mating of related individuals. It results in a decline in survival and reproduction (reproductive fitness), known as inbreeding depression, in most species of plants and animals. Outbreeding refers to matings between individuals from different populations, subspecies, or species.
What is meant by outbreeding depression?
In biology, outbreeding depression is when crosses between two genetically distant groups or populations results in a reduction of fitness. The concept is in contrast to inbreeding depression, although the two effects can occur simultaneously.