Taking Nature's Pulse - Biodiversity BC

taking nature’s pulse: the status of biodiversity in british columbiafigure 2:Conceptualpyramid of levelsof organizationof biodiversity.illustration:I. Houde.ECOSYSTEMSSPECIESGENES1.1.1 genetic, species and ecosystem diversityComplex concepts such as biodiversity are often easier to grasp if reduced to their component pieces. Whilethis approach does not give a complete picture of how these pieces interact and combine to create biodiversity,it helps us understand different aspects of biodiversity. The various levels of organization within biodiversity(e.g., genes, species and ecosystems) express different features of the complexity and value of biodiversity andinteract with each other through ecological processes. Genes make up species, and species (linked by ecologicalprocesses) inhabit ecosystems (Figure 2), with smaller ecosystems nested within larger ones. Ecosystems varyenormously in size. 11 They may be as tiny as a drop of pond water or a glacial rivulet, or as vast as the StikineRiver watershed, the northwest Pacific coast or the whole planet.genesGenes are the working units of heredity; each gene is a segment of the DNA molecule that encodes a singleenzyme or structural protein unit. Genetic diversity is the foundation of all biodiversity.. Genetic variationpermits populations to adapt to changing environments and continue to participate in life’s processes. Studyof subspecies and populations can reveal how organisms respond to their environment, which may not beevident when looking only at the species level. Genetic diversity is continuously changing from generation togeneration as a result of natural selection and random effects such as mutation.In the long history of life on earth, genetic variants of many species have evolved, and are still evolving,in response to changing local environmental conditions. For example, the current, highly productive runsin the Bristol Bay sockeye salmon (Oncohynchus nerka) fishery in Alaska originated from low-producingruns that responded to mid 1990s climate changes. 12 Figure 3 illustrates how genetic variations influencethe fur colour of the American black bear (Ursus americanus), which occurs as different colourmorphs (see also Section 2.4.1.2, p. 75).speciesSpecies (and their subspecies and populations) are generally considered to be the only selfreplicatingunits of genetic diversity that can function as independent units. In the case ofmost living organisms, each species generally represents a complete, self-generating,unique ensemble of genetic variation, capable of interbreeding and producing fertileoffspring. Some animals 13 and many plants 14 can also exchange genes throughhybridization, which sometimes results in new species (see Section 2.4.1.4, p. 82).