CH 18 BIODIVERSITY

Classification

• A species is defined by the ability of its members to breed and produce fertile offspring
• Species descend from a common ancestor
• A species shares the same genes, gene pool, and very similar biochemical, morphological, behavioral, and physiological features
• If animals, species share the same immunological features and occupy the same ecological niche

Scientific Naming

• The binomial system, based on Latin/Greek names, provides a universal identification using a generic name (genus) and a specific name (species)
• Names are italicized or underlined, with the generic name's first letter capitalized
• Unknown species are indicated by "sp.", pluralized as "spp." for multiple members of a genus
• Generic names can be abbreviated to the first letter after the initial use

Grouping and Taxonomy

• Classification organizes species into groups, with taxonomy studying these groups
• Artificial classification uses convenient differences, like color or size, and analogous features with similar functions but different evolutionary origins
• Phylogenetic classification reflects evolutionary relationships and descent using shared features from ancestors (phylogeny), with a hierarchical structure

Taxonomic Ranks

• Taxonomic ranks are hierarchical and include: domain, kingdom, phylum, class, order, family, genus, species
• Organisms are placed into domains, then kingdoms (largest groups), followed by phyla with distinct body plans, and further divided into classes, orders, families, genera, and species
• Homologous characteristics have similar evolutionary origins, regardless of function

Domains and Kingdoms

• Three domains of living organisms: Bacteria, Archaea, and Eukarya

Bacteria

• Single-celled prokaryotes lacking membrane-bound organelles
• Unicellular, with cells in chains or clusters
• Smaller 70S ribosomes
• Cell walls of peptidoglycan (murein)
• Circular, naked DNA lacking histones
• Typically 0.5-5.0 µm in length

Archaea

• Single-celled prokaryotes similar to bacteria
• Varying morphologies and habitats, common in extreme conditions
• Circular DNA and plasmids, without membrane-bound organelles
• Promoter regions of DNA similar to eukaryotes
• 70S ribosomes, structure differs from bacteria
• Membranes contain unique lipids such as ether lipids
• No peptidoglycan in cell walls

Eukarya

• Organisms with eukaryotic cells
• Chromosomes of linear DNA complexed with histone proteins and a nuclear envelope
• Membrane-bound organelles
• Cell walls (if present) lack peptidoglycan, e.g., cellulose in plants
• Larger 80S ribosomes (70S in mitochondria and chloroplasts)

Viruses

• Simple structures with nucleic acid (DNA or RNA) surrounded by a protein coat
• Not considered living and not included in the three-domain system
• Lack metabolism and require host cells to reproduce

Kingdoms of Eukarya

• Protoctista: unicellular or groups of similar eukaryotic cells; algae, Amoeba, Plasmodium
• Fungi: eukaryotic, heterotrophic via absorption, cell walls of chitin; moulds, yeasts, mushrooms
• Plantae: eukaryotic, multicellular with specialized tissues, autotrophic via photosynthesis; liverworts, mosses, trees
• Animalia: eukaryotic, multicellular with cellular organization, heterotrophic, no cell walls; diverse forms

Biodiversity

• Biodiversity includes genetic diversity, species diversity, and ecosystem diversity
• Genetic diversity allows species to adapt to changing conditions
• Species diversity includes species richness and relative abundance or evenness
• Ecosystem diversity enhances ecosystem functions and stability
• High diversity means increased stability and resilience to climate change
• Tropical rainforests have high biodiversity due to productivity, numerous species, high genetic diversity, many habitats, and consistent biological activity

Maintaining Biodiversity

• High biodiversity aids nutrient recycling, soil formation, and ecosystem integrity, which helps prevent floods and desertification
• Provides essential resources like food, fibers, medicines, and genetic diversity for adaptation
• Supports indigenous cultures, ecotourism, and research, and has aesthetic value

Ecological Terms

• Ecology studies organisms' interactions with the environment
• Environment includes biotic and abiotic components
• Ecosystems are functional units with energy flow and nutrient cycling
• Community: populations of different organisms in a place at the same time
• Population: group of organisms of the same species that interbreed
• Habitat: place where an organism lives
• Ecological niche: environmental conditions and resources required for a species

Food Chains and Webs

• Most producers are photosynthetic releasing oxygen as a byproduct
• Gross primary productivity (GPP) is the total production of organic food
• Net primary productivity (NPP) is the rate of production of organic food after respiration
• Consumers eat other organisms: herbivores, carnivores, and omnivores
• Detritivores decompose organic materials
• Food chains describe feeding relationships, each stage is a trophic level
• Food webs are interconnected food chains

Energy Transfer in Ecosystems

• Only a small percentage of the sun's energy is captured by producers
• Energy is lost due to reflection, absorption, respiration, and heat loss
• Carnivores are more efficient at transferring energy
• Inefficient energy transfer limits food chain length
• Ecological pyramids represent numbers, biomass, or energy at each trophic level

The Nitrogen Cycle

• A cyclical flow of nitrogen keeps necessary materials available
• Nitrogen cycle components: abiotic (rocks, atmosphere), biotic (producers, consumers, decomposers)
• Steps include: nitrogen fixation, ammonification, nitrification, assimilation, and denitrification
• Nitrogen fixation: converts nitrogen gas into useable nitrogen
• Assimilation: absorption of nitrates
• Ammonification: production of ammonia from nitrogen
• Nitrification: conversion of ammonium ions to nitrates
• Denitrification: reduction of soil nitrates into gaseous nitrogen

Ecological Techniques

• Small samples of an ecosystem are usually studied in detail
• Sampling techniques include: random sampling using frame quadrats and systematic sampling along transects

Random Sampling Using Frame Quadrats

• Important for the investigation to be unbiased
• Lay out two long tape measures and use random numbers from a table or calculator to determine place intersections
• Measurements: species density, frequency of occurrence, percentage cover, adundance scale

Systematic Sampling Along Transects

• Useful in circumstances where data can be obtained systematically
• Main types: line transect and belt transect, both can be continuous or interuppted

Mark-Release-Recapture Techniques

• Methods work well with plant communities but not with animals
• Number of animals are caught, marked in some way, and then released back into the community

Ecological Analysis

• Data collected from ecological studies requires analysis
• Statistical tests determine whether or not there is a relationship between two sets of data
• Tests include: Spearman's rank correlation, Pearson's correlation coefficient, Simpon's index of diversity

Spearmans Rank Correlation

• Meaures the relationship between two sets of ranked data
• Ordinal data are used or any data are coverted to an ordinal scale by using ranking
• More than five paired observations are needed, but 10 to 30 are ideal
• Represented equation: r = 1- (6 x ΣD)/(n³- n)

Pearson's Correlation Coefficient

• Is used to investigate the relationship between two quantiative, continuous variables
• Measures continuous variables rather than the categorical ones needed for Spearman's rank correlation

Threats to Biodiversity

• Habitat loss and fragmentation, competition from humans and other animals, hunting and poaching
• Climate change is putting a strain on ocean temperatures and coral as well as making the climate unpredictable which threatens biodiversity
• Pollution also poses a threat to different species survival

Protecting Endangered Species

• Development of national parks and nature reserves, legal protection for endangered species, Captive breeding in zoos and botanical gardens, seed/embryo/sperm banks, education
• Banning Hunting and Fishing with Commercial farming, removing animals from threatened areas

Conservation

• Conservation aims to protect and maintain earth's resources
• Assisted reproduction, culling and contraceptives, controlling alien species, and restoring degraded habitats are important to consider