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Biodiversity & “Nothing in Biology makes sense except in the light of evolution.” Evolution Theodosius Dobzhansky (1900-1975) geneticist & evolutionary biologist Image from https://www.genetics.org/content/202/1/5 Topic...

Biodiversity & “Nothing in Biology makes sense except in the light of evolution.” Evolution Theodosius Dobzhansky (1900-1975) geneticist & evolutionary biologist Image from https://www.genetics.org/content/202/1/5 Topic 1 At the end of the lesson, we hope to be able to ❏ define biodiversity (at the level of genes, species, and ecosystems) and ❏ relate biodiversity and evolution. 2  Activity 2 Defining biodiversity (pair or group of 3, 10 minutes) Watch a 4-min video. Consider the following questions while watching: 1. How was biodiversity defined in this video? 2. Why is biodiversity important? 3. How is biodiversity related to evolution? 4. How do human beings affect biodiversity? 4  Activity 1 Defining biodiversity (pair or group of 3, 10 minutes) Watch a 4-min video. Consider the following questions while watching: 1. How was biodiversity defined in this video? 2. Why is biodiversity important? 3. How is biodiversity related to evolution? 4. How do human beings affect biodiversity? Key Concept Biodiversity is the variety of life on Earth Biodiversity is the variety of life on Earth at all its levels, from genes to species to ecosystems, encompassing the evolutionary, ecological, and cultural processes that sustain life 6 Key Concept Biodiversity is the variety of life on Earth Genetic diversity refers to the variety of genes available in a population (gene pool). It enables adaptations in populations in response to environmental change. Species diversity or the number and abundance of species in a group in a given location maintains communities, nutrient cycling, and flow of energy. Ecosystem diversity or the collection of ecosystems in a given location is essential in providing critical life- sustaining services. 7  Provisioning Services -type of benefit to people that can be extracted from nature -food, drinking water, timber, wood, fuel, natural gas, oils etc. Valuing Biodiversity and Ecosystem Services Image from https://mjmerrick.files.wordpress.com 8  Regulating Services -services that make life possible for people -air filtration, water filtration, decomposition of wastes, pollination, prevention of soil erosion, etc. -services that moderate natural phenomena Valuing Biodiversity and Ecosystem Services Image from https://mjmerrick.files.wordpress.com 9  Cultural Services -non-material benefit that contributes to the development and cultural advancement of people -local, national and global cultures, building of knowledge, creativity born from interactions with nature (music, art, archi); recreation Valuing Biodiversity and Ecosystem Services Image from https://mjmerrick.files.wordpress.com 10  Supporting Services -consistency of underlying natural processes—photosynthesis, nutrient cycling, creation of soils, water cycle Valuing Biodiversity and Ecosystem Services Image from https://mjmerrick.files.wordpress.com 11 What happens to the number of species as you go from the poles to the equator? (7 mins) Why Do More Species Live Near the Equator? (712 mins) 13 Key concepts Species richness depends on availability of resources and niches Image from weebly.com 14 Key concepts Species richness depends on availability of resources and niches Biogeography studies the present and past distribution patterns of biodiversity, their environmental and historical causes, and conservation applications Image from weebly.com 15 Key concepts Species richness depends on availability of resources and niches Biogeography affects species diversity according to the following patterns: 1. Species richness increases as we travel from the poles to the equator due to climate conditions like amount of sunlight and availability of water. Areas near the equator may also be older allowing more time for evolution to occur. Image from weebly.com 16  Key concepts Species richness depends on availability of resources and niches Biogeography affects species diversity according to the following patterns: 2. Von Humboldt’s species-area curve (Figure 54.27) shows us that all factors being equal, species richness increases as the size of the available area increases because there are more available resources and more niches that can be filled. Image from weebly.com 17  Key concepts Species richness depends on availability of resources and niches Biogeography affects species diversity according to the following patterns: 3. Species richness on islands are affected by the size of the island and its distance from the source of organisms (mainland). There are less species on smaller islands that are farther from the mainland and their populations are also more extinction- prone. Image from weebly.com 18 Activity 3 Descent with modification (solo/pair, 30 mins) Evolution occurs at the population level. Populations are composed of freely interbreeding individuals. The collection of all the gene variants (alleles) in a Task 2: Add a post with population is called the gene pool. one of the scenarios from Steps 4/5 and a brief explanation for the observation. Evolution occurs when frequencies of alleles change within a population. 19  Activity 3 Descent with modification (solo/pair, 30 mins) 1. Visit the Population Genetics Simulator. 2. Read the Introduction. 3. Play with variables and see how the simulation works. 4. Find two different situations in which evolution occurs. 5. Find one situation in which evolution does not Task 2: Add a post with occur. one of the scenarios from Steps 6. Take a screenshot of one of these situations and 4/5 and a brief explanation for paste it under the Task 2 column of the class the observation. padlet. No repeating of parameters. 20 Key Concept Evolution is descent with modification Evolution is descent with modification. Species change over time, give rise to new species, and share a common ancestor. 21 Images from Bioninja, Tree of Life Web, UC Berkeley Key Concept Evolution is descent with modification Evolution can be studied on two scales: 1. Microevolution 2. Macroevolution 22 Images from Bioninja, Tree of Life Web, UC Berkeley Key Concept Evolution is descent with modification Microevolution occurs when there are changes in the frequencies of certain alleles (gene variants) within a population Mutation, selection, drift, and migration (gene flow) into or out of a population can result in microevolution. 23 Images from Bioninja, Tree of Life Web, UC Berkeley Key Concept Evolution is descent with modification Microevolution occurs when there are changes in the frequencies of certain alleles (gene variants) within a population 24 Images from Bioninja, Tree of Life Web, UC Berkeley Key Concept Evolution is descent with modification Mutation, selection, drift, and migration (gene flow) into or out of a population can result in microevolution. 25 Images from Bioninja, Tree of Life Web, UC Berkeley 26 Species are groups that can potentially interbreed*. They represent the biggest gene pool (collection of alleles/genes) possible under natural conditions. *These definitions do not apply to asexual organisms (bacteria, archaea, some plants).*. 27 Images from Bioninja, Tree of Life Web, UC Berkeley Speciation results from reproductive isolation*, nonviable offspring, and stops the sharing of genes within the population leading to formation of new species through evolution (increased species diversity). 28 Wrap-Up ★ Biodiversity is the variety of life on Earth at all its levels, from genes to species to ecosystems, encompassing the evolutionary, ecological, and cultural processes that sustain life ○ Genetic diversity refers to the variety of genes available in a population (gene pool). It enables adaptations in populations in response to environmental change. ○ Species diversity or the number and abundance of species in a group in a given location maintains communities, nutrient cycling, and flow of energy. ○ Ecosystem diversity or the collection of ecosystems in a given location is essential in providing critical life-sustaining services. 29 Wrap-Up ★ Evolution is descent with modification occurring at the population level but driven by genetic differences among individuals. 30 Wrap-Up ★ Populations share gene pools that contain all the genetic variations among individuals within the population. Evolution gives rise to biodiversity and diversity makes evolution possible. ○ For evolution to occur, a population must have genetic variation and experience at least one of the following: mutation, selection, migration or gene flow, genetic drift. 31 Phylogenies & Evolutionary Relationships Topic 2 Explaining the Tree of Life (5 mins) 33 The Tree of Life is a collaborative visual representation of the evolutionary history of all organisms. All species (at the tips of the branches) arose from a universal common ancestor (root) and are connected by the passage of genes along the branches of the tree. In this session, we will take a closer look at phylogenetic trees and how to interpret them. Images from http://tolweb.org/tree/ 34 At the end of the lesson, we hope to be able to ❏ define phylogenetics and its relation to systematics and taxonomy, ❏ describe the components of a phylogenetic tree, ❏ differentiate between monophyletic, paraphyletic, and polyphyletic groups, and ❏ relate shared characters with phylogenetic trees. 35 Key Concept Evolutionary history is the basis for natural classification schemes 36  Key Concept Evolutionary history is the basis for natural classification schemes Image from GoogleSites Taxonomy is the naming and classification of organisms traditionally done through a Linnaean binomial system (Genus species) and rank- based system (Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species). Organisms with similar characteristics are grouped together What is the dis/advantage of classifying organisms in this manner? 37 Key Concept Evolutionary history is the basis for natural classification schemes In the 1940s, Willi Hennig proposed using phylogeny or evolutionary history of a group of species, to group them together. Characteristics are used to discover this ancestry and relationships are visualized as trees instead of ranks. What is the dis/advantage of classifying organisms in this manner? 38 Key Concept Evolutionary history is the basis for natural classification schemes Image from GoogleSites Systematics is the branch of biology that uses evolutionary history and relationships (phylogeny) in naming and classifying organisms (taxonomy). 39 Key Concept Phenetics and phylogenetics are two main systems of classification PHENETICS - based on physical similarities without reflecting their evolutionary history ▪ artificial - based on one/ very few characters (e.g. Theophrastus and Linnaeus divided plants into herbs, shrubs, and trees) ▪ natural – classification of organisms based on numerous morphological and anatomical characters - resulting trees showing the similarities of organisms called phenograms 40 41 Key Concept Phenetics and phylogenetics are two main systems of classification PHYLOGENETICS - based on modern evolutionary theory, genetics, & computational tools and techniques - aims to reconstruct evolutionary relatedness and history of extant (currently surviving) species using morphological or molecular data arranged in phylogenies 42 Key Concept Phenetics and phylogenetics are two main systems of classification PHYLOGENETICS CLADISTICS PHYLETICS - based on assumptions about evolutionary - assumes new species gradually arise history - offers more information i.e., amount of - places species in groups called clades evolutionary change represented by the based on the order of descent from a branch lengths in phylograms common ancestor - closely related organisms are represented by shared features not present in the ancestor which are called shared derived characters/traits in cladograms 43