Ecology - Chapter 7

The sequence of events relating to its birth, growth, development, reproduction, senescence, and death

An organism’s life history

The overall pattern of life history events exhibited by all organisms within the species

Species’ life history strategy

When organisms allocate limited energy and resources to one structure or function at the expense of another

Trade-Offs?

Trade-Offs are not ____ choices

conscious decision-making

Large animals tolerate ___ environments best while small animals tolerate ___ environments best

cold ; warm

Large trees are less susceptible to ____ than small trees but are more susceptible to ____

fire ; wind

Allocating resources to reproduction takes resources away from what?

Growth, maintenance, and defense

Which species reproduce at a very early age?

Precocial

Example: Mayflies

Which species reproduce at a much later age?

Altricial

Example: Humans

Which organisms increase their fitness quickly in the population, but decrease their survival and future reproduction

Precocial

Example: Mayflies

Which species reproduce one time only?

Semelparous

Examples: Salmon, Mayflies, Annual Plants

Which species reproduce several times?

Iteroparous

Examples: Most trees, Birds, Mammals

Which organisms increase their fitness by reproducing more frequently?

Iteroparous

Examples: Most trees, Birds, Mammals

Which organisms increase their fitness by saving resources over time and producing the highest quality offspring all at once?

Semelparous

Examples: Salmon, Mayflies, Annual Plants

The _____ an organism’s energy investment in each individual offspring, the _____ offspring it can produce

larger ; fewer

An organism’s energy investment can be measured by the amount of ____ care provided

Parental

Organisms that provide parental care increase the chances of their offspring ___

surviving

Organisms that provide parental care produce far ____ offspring

fewer

The complete rearrangement of an organism’s body plan during its lifetime

Metamorphosis

Examples: Butterflies, Moths, Frogs, Salamanders

What are the advantages of metamorphosis?

Using different food sources and exploiting different habitats minimizes competition between the young and the adults of a species; Larval forms are usually small and excellent at dispersing (via water or wind) to colonize new habitats

Disadvantages of metamorphosis

Energetically very costly

The life histories of organisms often go beyond metamorphosis to include complex life cycles, give an example

Multiple hosts in the life cycle of parasitic worms ; Both sexual and asexual reproduction in the life cycle of corals ; An alternation of generations life cycle for plants

A reproductive cycle in plants, algae, and some fungi where an organism shifts between two distinct multicellular phases: a haploid gametophyte (by mitosis) and a diploid sporophyte (also by mitosis)

Alternation of Generations

What are the Resting Stages?

Resistant or inactive stages during periodic unfavorable conditions

Resting stages postpone _____ reproductive success and fitness for ______ reproductive success and fitness

immediate ; future (hopefully better)

Shorter lifespans mean early ____, but also shorter ______ times

mortality ; generation

Natural selection acts faster to ____ _____ _____ these short-lived species to their environments

more quickly adapt

Who developed a classification scheme for life histories in 1967?

Robert MacArthur and E.O. Wilson

What is the classification scheme for life histories developed by Robert MacArthur and E.O. Wilson?

r-selected strategies v. K-selected strategies

Traits of an r-selected species

Small size, early maturity/ reproduction (precocial), many small offspring, little parental care, short generation times, short lifespan/ early mortality, habitats that are frequently disturbed

Traits of a K-selected species

Large size, late maturity/ reproduction (altricial), few large offspring, much parental care, long generation times, long lifespan/ late mortality, habitats that are constant and predictable

Examples of r-selected species

Most insects (Mayflies) , small vertebrates (Mice) , and annual plants

Examples of K-selected species

Large mammals (elephants), large reptiles (tortoises and crocodiles), and large trees (oak)