1.1- Identifying, Naming, and Classifying Species Species is a group of organisms that can interbreed in nature and produce fertile offspring -there are approximately 2 million known species, but there is an estimated total of 5-20 million species on Earth -it is important to know the identity of species since there may be similar specimens that look similar but have completely different functions so knowing the identity of each specimen is important so you know which one you need Identifying Species: Using Species Concepts -scientists have been unable to agree on a single definition of what a species is -they have used the three most commonly used definitions instead, it is called the species concept -each concept focuses on a different aspect of an organism Species Concept Description Advantages and Disadvantages -focuses on the morphology of an Advantages organism; body shape, size and other -simple; most widely used method for structural features plants -relies on comparing measurements Disadvantages Morphological species concept and characteristics of similar -the challenge in having to decide how organisms much change between individuals is -after comparisons, scientists decide too much change whether similar organisms represent different species Biological species concept -defines species on the basis of Advantages whether two organisms can produce a -widely used my scientists fertile offspring Disadvantages -if two organisms can reproduce -cannot be applied in all cases naturally, then the two organisms are -some organisms reproduce asexually of the same species -cannot be applied to fossil species, they are no longer re producing Phylogenic species concept -focuses on the evolutionary history of Advantages an organism -can be applied to extinct species -species is defined as a cluster of -looks at the relationship among organisms that is different from organisms with DNA analysis others but shows a pattern of Disadvantages relationship between each other -evolutionary histories are not known for all species Naming Species -after deciding which organisms qualify as a separate species, a name must be assigned to the species -sometimes there are several names for one organism, being different in every r egion -having a standard system for naming organisms that can be understood by any scientist in the world is very important -taxonomy is the branch in biology that identifies, names, and classifies species -Carl Linnaeus, “Father of Taxonomy” is known for developing the system for naming species called binomial nomenclature -binomial nomenclature gives a two-word Latin name to each species -the first part is called the genus (can only be used once and is always capitalized) -the second part is the species (can be used several times and is never capitalized) -when typing the species name, it must be italicized -when writing the species name, it must be underlined Classifying Species -classification is the grouping of organisms based on a set of criteria that helps to organize and indicate evolutionary relationships -scientists need a set of agreed-upon rules o r criteria to help them classify species -hierarchical classification is the method of classifying organisms in which species are arranged in categories from most general to most specific
-taxonomic categories are groupings, arranged in a hierarchy, that are used to classify organisms that have been named and identified -there are eight taxonomic categories; domain, kingdom, phylum, class, order, f amily, amily, genus, species -the rank is a level in the classification scheme (class, order, family, etc.) -a taxon is a named group of organisms such as phylum Chordata or class Mammalia
1.2 Determining How Species Are Related Anatomical Evidence of Relationships -an ancestor is an organism (or organisms) from which other groups of organisms are descended -if two species share much of the same e volutionary history, it means that they may share an ancestor -anatomy is the branch of biology that deals with structure and form, including internal systems -biologists have discovered that the dinosaur and the bird have shared a much closer e volutionary relationship than they first thought -dinosaurs and birds also share similar skeletal structure and some dinosaur fossils have feathers too -comparing the skeletal structure of living organisms can also indicate a shared evolutionary Physiological Evidence of Relationships -physiology is branch of biology dealing with the physical and chemical functions of organisms, including internal process -by comparing proteins among different species, genetic similarities and differences can be determined -some organisms can be reclassified after technological advancements DNA Evidence of Relationships -genes are sections of DNA made of long chains of molecules called nucleotides -with technology, the sequence of nucleotides can now be determined -these sequences can be used to see if other organisms share the same or similar sequences which would mean they have shared evolutionary history -sometimes DNA evidence indicated unexpected relationships -for example, fungi and animals are more closely related than fungi and plants Phylogenetic Trees -a phylogenetic tree is a branching diagram used to show the evolutionary relationships among species -like a family tree, the roots or the base of the phylogenetic tre e represents the oldest ancestral species -the upper ends of the branches represent re present the present-day species that are r elated to the ancestral species -forks in each branch represent the points in the past at which an ancestral species split, evolved or just changed over time to become a new species The Importance of Classification to Technology, Society and the Environment -understanding the evolutionary relationships among species and groups of organisms can have important consequences in the medical field and also in the conservation of biodiversity -understanding phylogeny can help scientists trace the transmission of disease and develop and test possible treatment
1.3 Kingdoms and Domains The Six Kingdoms -structural diversity is a type of biological diversity that is exhibited in the variety of structural forms in living things, from internal cell structure to body morphology -until the 1800s, there were only two kingdoms; Plants and Animals and Animals -then the kingdom Protista was added to the classification system for single-celled organisms -in the early to mid 1900s, some single-celled organisms were found to be extremely small and without a cell nucleus so, Bacteria, Bacteria, was created -then fungi was found to be so different, so another kingdom was added -the bacteria kingdom was found to be too big, so it was divided into two, for a total of six kingdoms -three main ideas: •there are two main cell types that are significant for classification at the upper ranks like kingdom •the study of cell types and genes has led scientists to add a rank higher than kingdom - domain •it is important to understand how biologists think the domains and kingdoms are connected in their evolutionary history
Two Major Cell Types -if an organism is made up of one cell, it’s described as single -celled or unicellular -if an organism is made up of more t han one cell, it is multicellular -after centuries of study, biologists have agreed that ther e are two major types of cells; prokaryotic cells; prokaryotic and eukaryotic -prokaryotic cells are a smaller, simple type of cell that does not have not have a membrane-bound nucleus -are the most ancient cell type, still abundant today and me ans “before the nucleus”
-eukaryotic cells are a larger, complex type of cell t hat does have a membrane-bound nucleus -they have a much more complex internal structure and are about 1000 times larger than prokaryotic cells -eukaryotic means, “true nucleus”
-the two cells represent a major m ajor division in the structural diversity of life The Three Domains -as scientists continued to analyze the kingdoms Bacteria and Archaea, the category domain was added into the classification system -the differences between these two kingdoms were so great at the genetic and cellular level they had to put Bacteria and Archaea into different domains -as a result of reclassifying the kingdoms into domains, scientists decided to move the remaining kingdom, Eukarya, Eukarya, into a domain of its own -organisms in the two prokaryotic domains (Bacteria and Archaea) are unicellular, whereas both unicellular and multicellular organisms occur in Eukarya
Dichotomous Keys -the dichotomous key is an identification tool consisting of a series of two-part choices that lead the user to a correct identification of a specimen -the two-part choices are very simple, and they start from being broad generalizations, to being specific, eventually giving you the correct identification of the specimen -ultimate goal of the taxonomists is to identify at the species level -dichotomous keys can be also used to determine what kingdom an organism is in Main Characteristics of Kingdoms -there are 6 different kingdoms with many different characteristics Domain Bacteria Bacteri a Archaea Eukarya Bacteria Archaea Protista Plantae Fungi Kingdom Maple tree Mushroom Example Staphylococcus Sulfolobus Amoeba Archaea Prokaryote Prokaryote Eukaryote Eukaryote Eukaryote Cell Type Unicellular Unicellular and Multicellular Multicellular Number of Cells Unicellular Multicellular Peptidoglycan Occasionally no Cellulose in some; Cellulose Chitin Cell Wall cell wall occasionally no Material cell wall Nutrition Autotrophs and Autotrophs and Autotrophs and Autotrophs Heterotrophs heterotrophs heterotrophs heterotrophs Asexual Asexual Asexual and Sexual Sexual Reproduction sexual -an autotroph is an organism that obtains energy by making its own food, usually by sunlight -a heterotroph must consume other organisms to obtain energy
Animalia Rabbit Eukaryote Multicellular No cell wall
Heterotrophs Sexual
1.4 Classifying Types of Biodiversity -species diversity is the variety and abundance of species in a given area Genetic Diversity -genetic diversity is the variety of heritable characteristics (genes) in a population of interbreeding individuals -genes are the genetic material m aterial that controls the expression and inheritance of traits or characteristics -a variation among individuals in a population is a result of the differences in their genes -the genetic diversity among a population is known as a gene pool -genetic diversity within a species is greater than the genetic diversity within a population a population -too little genetic genetic diversity reduces a population’s ability to resist disease Ecosystem Diversity -ecosystem diversity is the variety of ecosystems in the biosphere -ecosystems are made up of two factors; abiotic (non-living) and biotic (living) -ecosystem services are the benefits experienced by or ganisms and are provided by sustainable ecosystems -for example, forests take up carbon dioxide and maintain soil fertility -resilience is the ability of an ecosystem to remain functional and stable in the presence o f disturbances to its parts -if an ecosystem has a high genetic diversity, it is more resilient to invasive diseases -humans may make changes to an ecosystem to enhance the se rvices of an ecosystem -for example, people may stock a lake with fish to provide recreational activities for others -sometimes, this affects the natural ecosystem of the area badly -in that example, after a four year study, the addition of non-native fish led to a reduced population numbers in amphibian species and changes in the number and variety of aquatic insect species
