Explain what you understand by the following with respect to author citation a) Olea europaea L.ssp . africana (Mill.) P . Green. b)Withamnia somnifera Dave ex Ross C)Acacia nilotica (Linn.)Michaux d)Solanum nigrum Brook et al. e)Opuntia pollardii Britt et Smith SECTION B:ANSWER ANY ONE QUESTION 20 MARKS) Question Eleven Discuss the different forms of isolation mechanisms and their role in the biological spec concept (20 IV Question Twelve Describe the process of preparing herbarium specimens ********************************************************************** **********************************************************************x=k=k=k ******************************************************************************************************************************************** (20 M

**Author Citation Explanation:**<br /><br />a) **Olea europaea L. ssp. africana (Mill.) P. Green**: This citation indicates that the subspecies "africana" of Olea europaea was originally described by Miller (abbreviated as Mill.) and later reclassified or revised by P. Green.<br /><br />b) **Withamnia somnifera Dave ex Ross**: In this citation, "Dave" is the person who first described the species but did not validly publish it, while "Ross" is the author who subsequently published the name validly.<br /><br />c) **Acacia nilotica (Linn.) Michaux**: This indicates that the species was originally described by Linnaeus (abbreviated as Linn.) and later revised or reclassified by Michaux.<br /><br />d) **Solanum nigrum Brook et al.**: The term "et al." means "and others," indicating that Brook and other authors contributed to the description or revision of this species.<br /><br />e) **Opuntia pollardii Britt et Smith**: This indicates that Britton and Smith are the authors who described or revised the species Opuntia pollardii.<br /><br />---<br /><br />**Question Eleven: Isolation Mechanisms in Biological Species Concept**<br /><br />Isolation mechanisms are critical in maintaining species integrity by preventing gene flow between different populations. These mechanisms can be prezygotic or postzygotic:<br /><br />1. **Prezygotic Isolation**: Prevents mating or fertilization between species.<br /> - **Temporal Isolation**: Species breed at different times.<br /> - **Habitat Isolation**: Species live in different habitats.<br /> - **Behavioral Isolation**: Differences in mating behaviors prevent interbreeding.<br /> - **Mechanical Isolation**: Physical differences prevent successful mating.<br /> - **Gametic Isolation**: Sperm and egg are incompatible.<br /><br />2. **Postzygotic Isolation**: Occurs after fertilization, reducing hybrid viability or fertility.<br /> - **Hybrid Inviability**: Hybrids fail to develop properly.<br /> - **Hybrid Sterility**: Hybrids are sterile (e.g., mules).<br /> - **Hybrid Breakdown**: Hybrids are fertile but their offspring are inviable or sterile.<br /><br />These mechanisms ensure that species remain distinct by limiting hybridization and promoting adaptation to specific ecological niches.<br /><br />---<br /><br />**Question Twelve: Preparing Herbarium Specimens**<br /><br />The process of preparing herbarium specimens involves several steps to ensure proper preservation and documentation:<br /><br />1. **Collection**: Gather plant specimens with all parts (leaves, flowers, fruits) intact. Note the location, date, habitat, and any other relevant information.<br /><br />2. **Pressing**: Place specimens between sheets of newspaper or blotting paper and press them using a plant press. Ensure specimens are spread out to display key features.<br /><br />3. **Drying**: Allow specimens to dry completely, usually in a warm, well-ventilated area. This prevents mold and decay.<br /><br />4. **Mounting**: Attach dried specimens to herbarium sheets using glue or tape. Include a label with collection details such as species name, collector's name, date, and location.<br /><br />5. **Labeling**: Provide detailed information on the label, including taxonomic identification, collection data, and any observations about the plant's ecology or morphology.<br /><br />6. **Storage**: Store mounted specimens in a controlled environment to protect them from pests, humidity, and light damage. Use archival-quality materials to ensure longevity.<br /><br />Herbarium specimens serve as valuable references for research, education, and conservation efforts.