B4.2 Ecological niches

name 3 types of organisms covered in this chapter

1. obligate aerobes

2. obligate anaerobes

3. facultative anaerobes

Holozoic nutrition in animals

1. ingestion

2. digestion

3. absorption

4. assimilation

Mixotrophic nutrition in some protists

capable of operating on a continuum from autotrophy to heterotrophy, instead of just one trophic mode

1. obligate mixotrophs: simultaneously use heterotrophic and autotrophic modes of nutrition to survive.

2. Facultative mixotrophs: sometimes heterotrophic only or autotrophic only

example is EUGLENA

Saprotrophic nutrition in some fungi and bacteria

saprotrophic organisms can be referred to as decomposers as they feed on decayed organic matter using enzymes (holozoic process same)

describe —Diversity of nutrition in archaea

archaea (one of the 3 domains of life) are nutritionally and metabolically very diverse. can either use

1. oxidation of carbon compounds/inorganic chemicals

2. light

to provide energy for atp production

—Relationship between dentition and the diet of omnivorous and herbivorous representative members of the family Hominidae

Carnivores have sharp canines/incisors to cut meat • Herbivores have large flat molars to grind fibrous plant tissue • Omnivores have a combination of modified sharp canines and large molars

Adaptations of herbivores for feeding on plants and of plants for resisting herbivory

1. leaf-eating insects have mandibles and piercings (to absorb sap)

2. plants produce toxic secondary metabolites (compounds commonly found in essential oils) in seeds and leaves that reduce the negative effects of predation.

—Adaptations of predators for finding, catching and killing prey and of prey animals for resisting predation

chemical, physical behavioural

Adaptations of plant form for harvesting light

Canopy trees have dominant vertical shoots that allow them to quickly reach the canopy to access light 2. Lianas climb other trees and use them for structural support to minimize the amount of energy needed to make structural support tissue like xylem 3. Epiphytes are non-parasitic plants that grow on the surface of other plants to structurally support themselves and reach light-rich areas without heavy investment into vertical growth 4. Strangler epiphytes (hemiepiphytes) initially live like normal epiphytes but then develop long roots that strangle the host tree’s roots and kill it 5. Shade-tolerant shrubs and herbs utilize light reaching the ground to grow instead of growing to tall heights through a unique set of photosynthetic pigments and larger leaf surface area

Fundamental and realized niches

The fundamental niche is the potential (theoretical) niche of a species based on tolerance limits and its adaptations. The realized niche is the actual extent of a species niche when biotic interactions (like competition) are factored in; it is only a part of the fundamental niche

explain competitive exclusion

Competitive exclusion is the principle that two species with overlapping fundamental niches cannot compete for the same resource too intensely for too long without having their demographics (population sizes) be affected. The superior competitor is the species that eventually outcompetes the other one. The inferior competitor is the species that is outcompeted by the other species and driven to extinction / elimination / exclusion.

One way to reduce the effects of competitive exclusion

niche partitioning; utilizing different parts of a species’ fundamental niche. This leads to the formation of realized niches (they are unique to every species on earth).