Ecology Competition Concepts Quiz

Yoda's Law (Self-Thinning Rule)

• As biomass increases, density decreases.

Competition

• Interaction reducing fitness of involved individuals.

Exploitative Competition

• Monopolizing resource access among individuals (also called resource competition or scramble competition).

Interference Competition

• Direct aggressive interactions between competitors (also called contest competition).

Intraspecific Competition

• Competition within the same species.

Interspecific Competition

• Competition between different species.

Detecting Competition

• Negatively correlated distributions: One species abundant where another is rare.
• Character displacement: Species are less similar in sympatric (same area) environments than allopatric (separate areas) environments.
• Removing a competitively dominant species: Removing a competitor increases the abundance of other species.
• Competitive exclusion: When two or more co-occurring species share a niche, the superior competitor drives inferior competitors to local extinction.

Coexistence

• Two species occupy the same niche simultaneously.

Conditions Favoring Coexistence

• Environmental variation: Different environments have certain effects on species. (e.g., mosquitofish are less aggressive in higher salinity water).
• Niche shift: Adaptive change in niche dimensions (habitat, diet, timing, location, activity, etc.).
• Niche partitioning: Dividing resources among competing species.

Types of Predators

• Carnivore: Sit & wait, stalk & chase, or trap predators. Low intimacy, High lethality.
• Herbivore: Grazers (grass) and Browsers (trees). Low intimacy, Low lethality.
• Parasite: Live on host organism. High intimacy, Low lethality.
• Parasitoid: Immature stage lives inside/on host, killing it when maturing.

Microparasites

• Live within cells, reproduce directly within host (e.g., viruses, bacteria, some protistans, simple fungi).

Macroparasites

• Visible to naked eye, live outside of host cells (e.g., ticks, nematodes, trematodes, some fungi).

Endoparasites

• Parasites that live within the body of their host.

Ectoparasites

• Parasites that live on the external surface of a host.

Hemiparasites

• Plant obtaining some nutrients from a host but also perform photosynthesis.

Holoparasites

• Obtain all nutrients from the host.

Batesian Mimicry

• A non-toxic organism resembles a toxic one.

Müllerian Mimicry

• Unrelated toxic species resemble each other.

Constitutive Defense

• Antipredator defense always present (e.g., thorns).

Secondary Metabolites

• Molecules not essential for growth, development, or reproduction.

Induced Defense

• Antipredator defense expressed in response to injury or threat.

Coevolution

• Process where two species evolve in response to changes in each other (Evolutionary arms race).

Red Queen Hypothesis

• Predators evolve faster to catch prey, and prey evolve to evade predators.

Mutualism

• Benefits both individuals (obligate or facultative).

Commensalism

• One individual benefits, the other is unaffected.

Generalist Bees

• Pollinate many species (wide niche). Losing these is worse than losing specialists.

Specialist Bees

• Pollinate only one species (small niche).

Colony Collapse Disorder

• Sudden absence of worker bees.

Neonicotinoid Pesticides

• Possible cause of colony collapse disorder, disrupting homing abilities and making bees more susceptible to parasitic mites.

Mycorrhizal Fungi and Plant Mutualism

• Mutualism where fungi acquire nutrients (N & P), and plants provide carbohydrates.

Coral and Zooxanthellae Mutualism

• Coral provides zooxanthellae with nitrogenous wastes, and zooxanthellae provide coral with carbohydrates.

Mutualisms and Commensalisms

• May provide: food/nutrients, different habitats, transportation, protection.

Resource Allocation

• Quantity of resources devoted to a particular process.

Life History Characteristics

• Evolved in response to resource allocation patterns → trade-offs.

Asexual Reproduction

• Eliminates need for mates but limits genetic diversity.

Parthenogenesis

• Offspring develop from unfertilized eggs.

Hermaphroditism

• Producing both male and female gametes.

Simultaneous Hermaphrodites

• Produce both gametes at the same time.

Sequential Hermaphrodites

• Change sex during development or in response to environment.

External Fertilization

• Female lays eggs, male fertilizes externally. Allows for many offspring.

Internal Fertilization

• Fertilization inside female's body. Improves mating success.

Oviparity

• Eggs laid outside the body (internal or external fertilization).

Viviparity

• Young develop in mother's body, nourished by mother.

Ovoviviparity

• Eggs develop in body, nourished by yolk, hatch within mother.

r-Selected Species

• High reproductive rates (rapid development, young age at maturity, many small offspring, low parental care).

K-Selected Species

• Greater competitive ability, lower reproductive rates (slow development, older age at maturity, few large offspring, high parental care).

Semelparity

• Produce many offspring only once in a lifetime.

Iteroparity

• Produce fewer offspring repeatedly throughout lifespan.

Altricial

• Helpless young at birth, requiring extensive parental care.

Precocial

• Relatively mature and mobile young at birth (more energy during gestation).

David Lack's Clutch Size Hypothesis

• Selection favors clutch size producing most surviving offspring (incorrect).

Offspring Size Factors

• Number of eggs (more eggs = smaller), resources (less resources = smaller offspring).

Species

• Interbreeding populations evolving independently.

Speciation

• Occurs when gene flow between populations is lacking. (Not true for asexual reproducers).

Morphospecies Concept

• Grouping species based on phenotypic similarities. Advantages: applies across many; Disadvantages: incorrect grouping/convergent evolution.

Phylogenetic Species Concept

• Identifying species based on monophyletic groups. Advantages: applies to all/testable; Disadvantages: arbitrary traits/expensive/many new designations.

Biological Species Concept

• Defining species by their ability to interbreed and produce fertile offspring. Advantages: lack of gene flow; Disadvantages: not testable for fossils/asexual species.

Speciation in Bacteria/Archaea

• Occurs due to gene flow.

Reduced Gene Flow Mechanisms:

• Physical isolation (allopatric speciation):
• Dispersal: Geographic isolation from moving to a new location.
• Vicariance: Geographic isolation when a range splits due to a new barrier.
• Mutation: Reduces gene flow even without separation.
• Polyploidy: Increase in chromosome number after meiosis error (important in plant speciation).

Phenotype Divergence Mechanisms

• Natural selection
• Sexual selection

Secondary Contact

• Two diverged species interbreed after migration/geographic change.

Prezygotic Isolation

• Mating does not occur; no offspring.

Postzygotic Isolation

• Hybrid offspring non-viable, sterile, or low fitness.

Hybridization Outcomes

• Reinforcement of postzygotic isolation: Hybrids have lower fitness and are selected against.
• Speciation: Hybrids develop distinct traits, potentially leading to a new species.
• Stable hybrid zones: Interbreeding reduces divergence between parent species.

Adaptive Radiation

• Rapid formation of many new species, often after a mass extinction or colonization of a new habitat.

Fossil Formation Types

• Compression Fossils: Formed in rock under physical compression.
• Unaltered Remains: Trapped in amber, frozen, or dried.
• Permineralization/Replacement: Dissolved minerals replace original material.
• Molds and Casts: Remains decay after burial revealing external/internal shapes.
• Trace Fossils: Record behavior (footprints, feces, burrows).

Dating Methods

• Radiometric dating: Dating rocks based on radioactive element decay.
• Stratigraphy: Relative ages from fossil layering.
• Molecular clock: Genetic divergence to estimate time since divergence.

Stromatolites

• Layered sediment cemented by microorganisms.

Precambrian Eon

• Hadean: Earth formed.
• Archean: First prokaryotes.
• Proterozoic: Anaerobic eukaryotes, photosynthesis evolution, emergence of metazoans.

Phanerozoic Eon: Paleozoic Era

• Cambrian: Cambrian explosion (animal diversity).
• Devonian: "Age of fishes," water-to-land transition, vascular plants, winged insects. Devonian extinction (cause unknown).
• Carboniferous: Tree ferns, conifers, amniotic eggs, coal formation.
• Permian: Anapsids, synapsids, diapsids, Permian extinction (largest mass extinction).

Phanerozoic Eon: Mesozoic Era

• Jurassic: Prosauropods, theropods (origin of birds), eutherian mammals.
• Cretaceous: First flowering plants, dinosaurs diversify. K-Pg extinction (asteroid impact).

Phanerozoic Eon: Cenozoic Era

• K-Pg extinction led to mammal radiation, hominid evolution.

Test your understanding of key concepts related to competition in ecology, including Yoda's Law and different types of competition such as exploitative and interference. Explore intraspecific and interspecific competition, along with methods for detecting competition among species.