Life Histories of Marine Organisms Flashcards

This set covers vocabulary and fundamental concepts of marine life history strategies, including resource allocation, fitness definitions, classification systems (r/K selection, Winemiller & Rose, Grime), and dimensionless analysis.

Life history

A species' lifetime pattern of growth, development, and reproduction.

Fitness

A measure of an organism's reproductive success, defined by those individuals who leave the largest number of mature offspring in their environments.

Trade-off

A compromise between conflicting demands, such as the relationship between the number and size of offspring, where producing larger offspring constrains an organism to produce fewer.

Gene flow

Also known as gene migration, it is the transfer of alleles or genes from one population to another.

Gonadosomatic Index (GSI)

A measure calculated as $100 \times \frac{\text{ovary mass}}{\text{body mass}}$ or as ovary weight divided by body weight adjusted for the number of batches produced per year.

r selection

Selection favoring a higher population growth rate, calculated as $r = \frac{\text{ln } R_0}{T}$, often found in species colonizing new or disturbed habitats.

K selection

Selection favoring more efficient utilization of resources, prominent where populations are near the carrying capacity ($K$) of the logistic growth equation $\frac{dN}{dt} = r_{max}N(1 - \frac{N}{K})$.

Ruderal strategy

A life history strategy in plants (Grime 1979) characterized by high disturbance and low stress, exemplified by species like \textit{Enteromorpha sp.}

Stress-tolerant strategy

A life history strategy in plants characterized by high stress and low disturbance, exemplified by species like \textit{Pelvetia canaliculata}.

Competitive strategy

A life history strategy in plants favoring environments with low stress and low disturbance.

Opportunistic life history

A classification (Winemiller & Rose 1992) characterized by low juvenile survival ($l_x$), low fecundity ($m_x$), and early reproductive maturity ($\alpha$).

Periodic life history

A classification characterized by low juvenile survival ($l_x$), high fecundity ($m_x$), and late reproductive maturity ($\alpha$) to take advantage of infrequent favorable conditions.

Equilibrium life history

A classification combining high juvenile survival ($l_x$), low fecundity ($m_x$), and late reproductive maturity ($\alpha$).

Relative offspring size

In Charnov's (2002) dimensionless analysis, the size of offspring expressed as a proportion of adult body mass, calculated as $I/m$.

Relative reproductive life span

The average length of a species' reproductive life divided by the time required to reach reproductive age, calculated as $E/\alpha$.

Relative reproductive effort

The fraction of adult body mass allocated to reproduction over a life span, calculated as $C \times E$.

Random distribution

A pattern where an individual has an equal probability of occurring anywhere in an area, resulting from neutral interactions.

Regular distribution

A pattern where individuals are uniformly spaced, often due to antagonistic interactions or local depletion of resources.

Clumped distribution

A pattern where individuals live in areas of high local abundance separated by low abundance, due to attraction to common resources or limited dispersal.

Semelparous

Organisms that reproduce once in their lifetime, such as the salmon species \textit{Oncorhynchus}.

Iteroparous

Organisms capable of multiple reproductive cycles over their lifetime, such as the brown trout (\textit{Salmo trutta}) or Cod (\textit{Gadus morhua}).

Alevin

A developmental stage of fish like the brown trout where the young use up a yolk sac while remaining in the gravel.

Smolt

The life stage where young fish return from the river to the sea after 1-4 years.

Eurytopic

Organisms that are not physiologically specialized and tend to be adaptable to various environments, often seen in opportunistic macroalgae forms.

Stenotopic

Organisms that are specialized physiologically and restricted to a narrow range of environmental conditions, often seen in late successional macroalgae forms.