Biotic Interactions and Life Strategies: Linking Fitness, Reproduction, And Parental Care

Basic terms

• Population Growth

• Biotic Interactions

• Life History Strategies

• Fitness

• Influence of Predation

• Influence of Completion

• Predation

• Competition

Population Growth

Influenced by birth and death rates, which are impacted by biotic interactions

Biotic Interactions

Predation/competition shape survival and reproduction, key factors in population growth

Life History Strategies

Evolutionary adaptations influence an organism reproductive schedule and survival.

Fitness

Individuals ability to survive and reproduce 

Influence of Competition

Limited resources can lead to adaptations that maximize resource use efficiency, which could optimize reproductive success in some individuals.

Predation

Species in predator-heavy environment often reproduce rapidly with less parental care.

Competition

Species in resource-limited environments may have fewer offspring but invest heavily in each one. 

Reproduction is essential for population growth

• Intraspecific competition and social system can restrict reproduction is some individuals

• Environmental conditions/resources can limit reproduction at times

Fitness influences on reproduction

Ability to leave behind offspring

• Transmission of genetic information/traits from one generation to another

*A lot of energy and most of life is spent mating and taking care of offspring (trees produce seeds) 

Types of Reproduction

1) Asexual Reproduction

• Offspring genetically the same as parents 

• Variety of means: Binary Fission, rhizomes, and Parthenogenesis. 

2) Sexual Reproduction 

• Production of haploid gametes (produces a diploid zygote) 

• Variety forms: dioecious, monoecious, hermaphroditic, etc. 

Types of Mating 

1) Monogamy 

2) Polygyny 

3) Polyandry 

Monogamy 

• 1 male and female mate 

• Brief or long-lasting bond 

• Regular/moderately clumped distribution (eg, dispersion patterns) of resources 

common in birds 

Polygyny 

• 1 male, several females

• Can be intense competition between females (intraspecific competition) 

types: 

1) Female defense polygyny (harem defense) (female groups from)  

2) Resource defense polygyny (males defend an aggregated resource) 

Major Difference of Reproductive Potential

Females

• Finite # of eggs 

Males

• Produce sperm continuously 

General Consequences of the Asymmetry in investment by males and females

Success is limited by # of young she can produce. For males, success is determined by # of receptive males he can inseminate. 

Reproductive Strategies in Sex that invests less (usually males)

1) Development of traits (secondary sexual characters) that allow them to compete with other males 

2) Characters that make them attractive to the other  gender (Plumage, behavior) 

Development of other important traits

• Endurance (stamina, energy) and large body size 

• Some species require ovulation to be induced. 

Handicap Principles

Certain costly and seemingly disadvantageous traits in animals may actually function as honest signals of genetic quality or fitness. 

• Despite being energetically costly and increasing predation risk, these traits persist due to mating advantages (peacock tail, deer antlers, colourful fish, birds, bird songs, and dances. 

General Rule (females)

Females should be choosy about mate

• Females that look for good genes will pick male that proves they can make “healthy” and “many” babies 

Females looking for resources 

• Pick mate that will help her get access to resources, nesting areas or simply that will help with parental care. 

Influences of parental care

• Type of mating system

• Taxonomic group

• Habitat

Mammals (Parental care)

Females play a bigger role (especially in polygamous species) (exceptions are monoganous species)

Birds (Parental care) 

Both males/females usually play an important role (exceptions are polyandrous species) 

Parental care includes 

• Food 

• Shelter 

• Protection 

• Grooming 

Altricial Offspring

When born, you need protection (karagroo)

Precocial offspring

Born quickly and little independent (whales and deer) 

Male parental care

Many species (especially monogamous species), males invest in parental care to increase the survival of offspring.

ex; Stickleback, glass frog, southern care, red phalarope.

Characteristics of parental care (plants)

The seed-producing parent has a nurturing role in developing seeds. 

• Can use the size of the seed to indicate parental care.