Transcript Slide 1
Pertemuan 3 BIOSISTEMATIKA SEBAGAI DASAR BIOKONTROL NILAI PENTING BIOSISTEMATIKA DALAM BIOKONTROL Identifikasi merupakan langkah awal dalam biokontrol; Sering terjadi salah identifikasi karena adanya spesies kembar dan atau polymorfisme serta proses adaptasi evolusi (perubahan jenis pakan, habitat dll) Minimal terdapat 2 kelompok organisme yang terlibat (target dan agen); Perlunya penentuan spesies-spesies target secara tepat dengan karakter-karakter molekuler – ekologinya. Perlunya mencari musuh-musuh alami di habitat yang sama dengan spesies target atau pada habitat lain Pengembangan teknik biokontrol modern (aplikasi biopestisida – rekayasa genetik) perlu karakter-karakter biokimia - molekuler What is biosystematic? • Taxonomy is the study of classification, its principles, procedure and rules • Classification is the ordering of organisms into classes or groups • Systematics is the branch of biology that’s concerned with the comparative study of organisms and all relationships among them • Biosystematics is the application of genetics (and cytogenetics) , statistics and chemistry to the solution of systematics questions in order to provide explanations abaout the diversity of organisms within the frame of the theory of evolution Types of relationships between organisms • relationships of descent (phylogenetic relationships) • relationships of similarity (phenetic relationships) • spatial or geographical relationships • trophic relationships The force of chnge to the variability of different generation (phylogenetic variability): • mutation • recombination • selection • gene flow •Random phenomena Pattern of phenetic variability: • geographical variability ecotypes • ages-based variability • sex-based variability • plasticity Macroevolution is the origin of new taxonomic groups, as opposed to microevolution, which is genetic variation between generations within a species. What is a species? 1. Biological species concept - A species is a population or group of populations whose members have the potential to interbreed with one another and produce viable offspring, but who cannot produce viable offspring with other species. The biological species concept is based on inter-fertility, rather than physical similarity. Speciation - process by which a new species originates. - Involves the creation of a population of organisms that are novel enough to be classified in their own group. - Two processes by which this can occur: - Anagenesis is the accumulation of heritable traits in a population, that transforms that population into a new species. - Cladogenesis is branching evolution, in which a new species arises as a branch of from the evolutionary tree. The original species still exists. This process is the source of biological diversity. The problem with the idea of biological species concept --> How do you get organisms to breed to see whether viable offspring are produced? There are… Alternative concepts of species a. Ecological species concept - Species are defined by their use of environmental resources; their ecological niche (e.g. species that are defined by their food source such as butterflies with certain flowers). b. Pluralistic species concept - Factors that are most important for the maintenance of individuals as a species vary. These factors include reproductive isolation, i.e. not being in the same area so mating is precluded. c. Morphological species concept - Species are characterized according to a unique set of structural features. This is still the most widely used concept by taxonomists. d. Genealogical species concept - Recognizes species are sets of organisms with unique genetic histories. This idea is based often on molecular analyses such as DNA sequences. Modes of speciation 1. Allopatric speciation - Allopatric speciation describes speciation that takes place in populations with geographically separate ranges. Gene flow is interrupted and new species evolve. 2. Sympatric speciation - Sympatric speciation describes speciation that takes place in geographically overlapping populations. Chromosomal changes and nonrandom mating reduce gene flow. Remember: Species arise when individuals in a population become isolated one from the other.