Adaptation to Environment & Ecological Niches

Reticulated Giraffe and Ecosystems

  • The reticulated giraffe (Giraffa reticulata) resides in its native habitat of Kenya.

    • This species and all other organisms in the ecosystem are well adapted to their environment.

Ecological Adaptations and Evolution

  • Organisms in ecosystems generally experience co-evolution and adaptation over thousands of generations.

    • Each generation carries genetic information that conveys efficient adaptations necessary for survival in a specific habitat.

    • Evolution introduces minor genetic changes in response to environmental shifts.

Interdependence of Organisms

  • In an ecosystem, organisms depend on one another for survival. This dependence ranges from simple nutritional exchanges to complex interspecies interactions.

    • Example: One species may provide nutrition for another.

Describing Habitats

  • Ecological habitats can be characterized by their geographical and physical parameters, as well as the ecosystem type present.

    • Geographical Location: Determines specifics like GPS coordinates; however, this doesn't convey the richness of the ecosystem.

    • Systematic Description: Better understanding comes from describing the ecosystem, including features like sawgrass, water bodies, and predominant species (e.g., alligators, birds).

Adaptation to Environment

Adaptations and Habitats

  • Habitats fulfil the basic requirements necessary for the survival of organisms, including:

    • Shelter

    • Food

    • Water

    • Oxygen

    • Nutrients and light (for photosynthetic organisms)

  • Adaptative traits develop over time, supporting organism success in their specific habitat.

  • Habitats evolve over time, necessitating adaptive changes in the resident organisms.

Terrestrial Biomes and Their Predictability

  • Biomes are distinguishable terrestrial areas defined by consistent annual precipitation and temperature patterns.

    • Convergent evolution is evident in organisms within the same biome addressing physiological challenges similarly.

Habitat Definition

What is a Habitat?

  • A habitat is defined as the location where a community, species, or population of organisms exists.

    • The description encompasses both its geographical and physical characteristics during the organism's lifecycle.

Adaptations to Abiotic Environments

Examples of Environmental Adaptations

  • The document provides two species examples demonstrating adaptation to challenging abiotic environments: sand dune grasses and mangroves.

Sand Dune Grasses

  • Species: Sea oat (Uniola paniculata)

    • Grows on sand dunes along the U.S. eastern seaboard.

    • Adapts to drought with:

    • Shallow root systems.

    • Narrow leaves to minimize water loss through transpiration.

    • Closing of stomata in extended dry conditions.

    • Dense, interwoven root systems to stabilize sand and maximize water uptake.

    • Sea oats can withstand saltwater immersion briefly and produce asexual shoots (rhizomes) when covered by sand, enabling survival and reproduction.

Mangrove Trees

  • Species: Red mangrove (Rhizophora mangle)

    • Grows in tropical and subtropical saltwater tidal zones (e.g., Bermuda, Florida).

    • Notable adaptations:

    • Prop roots providing stability and air absorption above water, aiding oxygenation of submerged root tissues.

    • Salt filtration capabilities ensuring access to freshwater.

    • Provides nursery habitats for many aquatic organisms, with roots minimizing erosion and storm impact.

Abiotic Variables Affecting Species Distribution

Abiotic Factors Overview

  • Unliving components significantly impact living organisms' distribution.

    • Common abiotic factors:

    • Water availability

    • Temperature range

    • Light intensity and duration

    • Soil composition

    • pH range

    • Salinity

  • The distribution of species can be influenced by tolerance ranges related to these abiotic factors, and any fluctuations may act as limiting factors.

Limiting Factors

  • A limiting factor can be either abiotic or biotic, restricting the population size or presence of aSpecies:

    • Examples include conducting experiments to determine levels of specific abiotic factors and their correlation with species abundance.

Practical Application

  • Students should utilize transect data in experiments to measure and analyze population sizes relative to abiotic variables in natural or semi-natural habitats.

Coral Reef Formation

Conditions for Coral Reef Formation

  • Coral reefs exist in less than 1% of the ocean's surface yet host approximately 25% of all marine species.

    • Formed by a symbiotic relationship between coral polyps and zooxanthellae algae.

    • Require specific abiotic conditions, including:

    • Water depth: Light penetrates only shallow waters, essential for photosynthesis of zooxanthellae.

    • Temperature range: Corals thrive at temperatures between 20°C and 28°C; global warming induces stress and bleaching.

    • Salinity: Freshwater runoff disrupts the appropriate salinity balance necessary for corals.

    • Water clarity: Sediment and pollutants can limit the amount of light reaching corals.

    • Water pH: Ocean acidification from increased CO₂ lowers pH and reduces calcium carbonate availability for reef building.

Terrestrial Biomes

Abiotic Factors Determining Biome Distribution

  • A biome represents a large geographical area characterized by specific communities of plants and animals adapted to environmental conditions.

    • Biomes can be predicted based on temperature and rainfall.

    • Various locations may share biome characteristics independent of geographical boundaries (e.g., deserts across continents exhibits various species sharing adaptations).

Differences Between Biomes

  • Potential examples include:

    • Hot desert: Less than 300 mm rainfall per year, significant temperature extremes.

    • Temperate forest: Moderate precipitation range with richer biodiversity.

Adaptations in Ecosystems

Adaptation Strategies in Hot Deserts

  • Example: Saguaro cactus (Carnegiea gigantea)

    • Adaptations include a thick, waxy exterior, long taproots for deep water access, and shallow roots to capture rainwater, facilitating survival during droughts.

    • Slow growth—reach full height (up to 14m) at the age of about 200 years.

Adaptation Strategies in Tropical Rainforests

  • Example: Kapok tree (Ceiba pentandra)

    • Characterized by rapid vertical growth to reach canopy light, buttress roots for stability in shallow soil.

    • Example: Poison-dart frogs are adapted for survival in humid environments, with dietary toxins as defense mechanisms and bright colors showcasing toxicity to predators.

Ecological Niches

Ecological Niches Overview

  • All organisms occupy unique roles within an ecosystem encompassing their spatial habitat, feeding activities, and interactions.

Fundamental vs. Realized Niches

  • The fundamental niche represents the potential environment based on adaptations.

  • The realized niche reflects actual inhabitance impacted by competition, for example, the red fox's habitat changes due to agricultural expansions and competition with coyotes.

Competitive Exclusion

  • The principle of competitive exclusion dictates that two species vying for identical niche spaces cannot coexist, leading to one species out-surviving or forcing the other to niche down due to diminished resources.

  • Historical experiments (Gause's Paramecium) demonstrated that competitive pressures limit biological diversity that can truly coexist.