Ecology: Niches, Autotrophs, and Plant Adaptation

• These are important notes and topics related to niches, autotrophs, heterotrophs, plant adaptations, and population demography in ecology.

Niches

• Fundamental niche includes environmental conditions and resources needed for a species to grow, survive, and reproduce.
• Realized niche is the actual niche occupied by a species, which is altered due to interactions with other species.
• Habitat is a place with specific environmental conditions, resources, and organisms, often confused with niche.

Autotrophs

• Photoautotrophs utilize light as their energy source.
• Light compensation point is when CO2 uptake by photosynthesis equals CO2 loss by respiration.
• Light saturation point is the point at which photosynthesis no longer increases with increasing light intensity.
• Acclimatization to low light involves morphological changes like thicker leaves and more chloroplasts, plus adjustments in pigment density and enzyme concentrations.

Plant Adaptations

• Transpiration is the process of water uptake and loss in plants.
• Vascular plants move water from soil to roots, through the stem, and out of leaves via transpiration.
• Gas exchange occurs through stomata in leaves.
• Stomata can close to conserve water or open for gas exchange as needed.
• In C3 plants, photorespiration occurs when O2 reacts in the Calvin cycle, forming toxins and reducing photosynthetic efficiency.
• Photorespiration increases with low CO2 levels inside the leaf caused by high light, high temperature, low moisture, or low atmospheric CO2.
• CAM plants use carbon concentrating mechanisms to avoid photorespiration, an adaptation to low root water intake.
• Terrestrial plants have more carbon available for glucose and cellulose cell walls due to their structure, which allows them to compete for light and water.

Liebig’s Law of the Minimum

• Growth is limited by the nutrient available at the lowest concentration relative to the species' needs.
• This law is most applicable when one nutrient is significantly lower in availability than others. Natural systems often have multiple limiting nutrients.

Chemotrophs

• Chemotrophs derive energy from inorganic compounds to synthesize organic compounds.
• Chemosynthesis produces H+ as a waste product, acidifying soil and water.

Heterotrophs

• Heterotrophs use organic carbon as their carbon source, often recycling monomers.
• Herbivores consume plants.
• Detritivores like earthworms and fungi consume dead organic matter.
• Predators consume other animals.
• Parasites live on or in a host organism.
• E. coli is metabolically challenged because it must synthesize its own fuel.

Heterotroph Diets Adaptations

• Assimilation of plant-based food can be inefficient as food composition is dissimilar to consumer tissue.
• Plant consumers may rely on microbial symbionts to aid digestion. Plants, as food sources, are abundant and stationary.
• Assimilation of animal-based food is usually efficient due to the similarity between food and consumer tissue.
• Predators must adapt to mobile prey.
• Optimal foraging theory suggests behavior maximizes return on investment, considering both nutrient content and energy.
• Animals face tradeoffs between different food patches, described by the marginal value theorem, which suggests their behavior corresponds with these tradeoffs.

Population Dynamics

• Population size at time t+1 (N t+1) is determined by the population size at time t (N t) plus births (B) minus deaths (D), plus immigration (I) minus emigration (E).
• Ignore immigration and emigration for now.
• A genet is a unique genetic individual.
• A ramet is a physiologically unique, or apparently unique individual.

Demography and Life Table

• lx = survivorship: proportion of individuals surviving from birth to age x, calculated as (Nx / N0).
• Fx = fecundity: average number of offspring produced per surviving adult per age class, calculated as (Nx offspring / Nx).

Explore ecological niches, distinguishing between fundamental and realized niches. Learn about autotrophs, including photoautotrophs, light compensation points, and acclimatization to low light. Discover plant adaptations and population demography, focusing on survival strategies and environmental interactions.