Comparisons of invasive plants in southern Africa originating from southern temperate, northern temperate and tropical regions

Bothalia ◽  
2006 ◽  
Vol 36 (2) ◽  
pp. 201-222 ◽  
Author(s):  
L. Henderson
Keyword(s):  
Southern Africa ◽  
Temperate Species ◽  
Tropical Species ◽  
Alien Plant ◽  
Important Species ◽  
Tropical Regions ◽  
Invasive Alien Plant ◽  
Rate Of Spread ◽  
Tropical America ◽  
The Tropics

A subset of invasive alien plant species in southern Africa was analysed in terms of their history of introduction, rate of spread, countries/region of origin, taxonomy, growth forms, cultivated uses, weed status and current distribution in southern Africa, and comparisons made of those originating from south of the tropic of Capricorn, north of the tropic of Cancer and from the tropics. The subset of 233 species, belonging to 58 families, includes all important declared species and some potentially important species. Almost as many species originate from temperate regions (112) as from the tropics (121). Most southern temperate species came from Australia (28/36), most tropical species from tropical America (92/121) and most northern temperate species from Europe (including the Mediterranean) and Asia (58/76). Transformers account for 33% of  all species. More transformers are of tropical origin (36) than of northern temperate (24) and southern temperate origin (18). However. 50% of southern temperate species are transformers, compared to 32% of northern temperate and 29% of tropical species. Southern temperate transformer species are mainly woody trees and shrubs that were established on a grand scale as silvicultural crops, barriers (hedges, windbreaks and screens) and cover/binders. Most aquatics, herbs, climbers and succulent shrubs an. trom the tropics. Ornamentals are the single largest category of plants from all three regions, the tropics having contributed twice as many species as temperate regions.

scholarly journals Macroecology of parental care in arthropods: higher mortality risk leads to higher benefits of offspring protection in tropical climates

2019 ◽  
Author(s):  
Eduardo S. A. Santos ◽  
Pedro Penna Bueno ◽  
James Gilbert ◽  
Glauco Machado
Keyword(s):  
Parental Care ◽  
Mortality Risk ◽  
Natural Enemies ◽  
Field Experiments ◽  
Biotic Interactions ◽  
Tropical Species ◽  
Tropical Regions ◽  
Offspring Protection ◽  
Tropical Climates ◽  
The Tropics

The intensity of biotic interactions varies around the world, in such a way that mortality risk imposed by natural enemies is usually higher in the tropics. A major role of offspring attendance is protection against natural enemies, so the benefits of this behaviour should be higher in tropical regions. We tested this macroecological prediction with a meta‐regression of field experiments in which the mortality of guarded and unguarded broods was compared in arthropods. Mortality of unguarded broods was higher, and parental care was more beneficial, in warmer, less seasonal environments. Moreover, in these same environments, additional lines of defence further reduced offspring mortality, implying that offspring attendance alone is not enough to deter natural enemies in tropical regions. These results help to explain the high frequency of parental care among tropical species and how biotic interactions influence the occurrence of parental care over large geographic scales. Finally, our findings reveal that additional lines of defences – an oftentimes neglected component of parental care – have an important effect on the covariation between the benefits of parental care and the climate‐mediated mortality risk imposed by natural enemies.

Climate Change in the Tropics: Ecological and Evolutionary Responses at Low Latitudes

2019 ◽  
Vol 50 (1) ◽  
pp. 303-333 ◽  
Author(s):  
Kimberly S. Sheldon
Keyword(s):  
Climate Change ◽  
Life Histories ◽  
Research Priorities ◽  
Tropical Species ◽  
Polar Regions ◽  
Ecological Communities ◽  
Tropical Regions ◽  
Current State ◽  
The Tropics ◽  
Impacts Of Climate Change

Climate change is affecting every ecosystem on Earth. Though climate change is global in scope, literature reviews on the biotic impacts of climate change have focused on temperate and polar regions. Tropical species have distinct life histories and physiologies, and ecological communities are assembled differently across latitude. Thus, tropical species and communities may exhibit different responses to climate change compared with those in temperate and polar regions. What are the fingerprints of climate change in the tropics? This review summarizes the current state of knowledge on impacts of climate change in tropical regions and discusses research priorities to better understand the ways in which species and ecological communities are responding to climate change in the most biodiverse places on Earth.

scholarly journals Changes in the composition and distribution of alien plants in South Africa: An update from the Southern African Plant Invaders Atlas

Bothalia ◽  
2017 ◽  
Vol 47 (2) ◽  
Author(s):  
Lesley Henderson ◽  
John R.U. Wilson
Keyword(s):  
South Africa ◽  
Classical Biological Control ◽  
Alien Plants ◽  
Detectable Effect ◽  
Alien Plant ◽  
Invasive Alien Plant ◽  
Plant Invaders ◽  
Rate Of Spread ◽  
Control Programmes ◽  
Relative Change

Background: Data on alien species status and occurrence are essential variables for the monitoring and reporting of biological invasions. The Southern African Plant Invaders Atlas (SAPIA) Project has, over the past 23 years, atlassed alien plants growing outside of cultivation. Objectives: To document changes in the alien plant taxa recorded in SAPIA, assess trends in invasive distributions and explore effects of management and regulations.Method: The numbers of alien plant taxa recorded were compared between May 2006 and May 2016, and changes in the extent of invasions at a quarter-degree squares (qds) scale were compared between 2000 and 2016. The effectiveness of regulations and interventions was assessed in terms of the relative change in the extent of invasions. Results: As of May 2016, SAPIA had records for 773 alien plant taxa, an increase of 172 since 2006. Between 2000 and 2016, the number of qds occupied by alien plants increased by ~50%, due both to ongoing sampling and to spread. Successful classical biological control programmes have reduced the rate of spread of some taxa and in a few cases have led to range contractions. However, other interventions had no detectable effect at a qds scale. Conclusions: South Africa has a growing number of invasive alien plant species across an increasing area. More taxa should be listed under national regulations, but ultimately more needs to be done to ensure that management is strategic and effective. SAPIA is a valuable tool for monitoring alien plant status and should be developed further so that invasions can be accurately tracked over time.

Insecticidal Activities of the Leaf Extract of the Invasive Alien Plant, Chromolaena odorata (L.) (Asteraceae) Against Macrotermes species (Termites)

2019 ◽  
Vol 35 (1) ◽  
pp. 145-153
Author(s):  
O. Uyi, ◽  
I.G. Amolo ◽  
A.D. Adetimehin
Keyword(s):  
Leaf Extract ◽  
Insect Pests ◽  
Chromolaena Odorata ◽  
Leaf Extracts ◽  
Alien Plant ◽  
Biological Efficacy ◽  
Invasive Alien Plant ◽  
Impregnation Technique ◽  
Aqueous Leaf Extract ◽  
Worker Caste

Several studies have demonstrated the biological efficacy of leaf, stem and root powders or extracts of Chromolaena odorata (L.) King and Robinson against insect pests but those that are focused on the biological efficacy of aqueous leaf extracts against Macrotermes species are scanty. Current management of termites with synthetic insecticides is being discouraged due to human and environmental hazards. Therefore, the insecticidal effectiveness of aqueous leaf extract C. odorata against Macrotermes species was investigated. Five concentrations (0, 2.5, 5.0, 7.5 and 10.0% (w/v)) of the aqueous extract of C. odorata plant were evaluated for repellency and toxicity on the worker caste of Macrotermes species following standard procedures. The filter paper impregnation technique was used for the bioassay. Percentage repellency was monitored for 30 minutes and mortality recorded at 12, 24 and 36 hours post exposure. The leaf extract of C. odorata significantly repelled 95% of Macrotermes species at the highest concentration of 10% (w/v) after 30 minutes post treatment exposure. Mortality of Macrotermes species was independent of treatment concentration, but dependent on duration of exposure. All treatment concentrations of aqueous leaf extract of C. odorata caused significant mortality against Macrotermes species ranging between 94% and 98% compared to the control; indicating very great potential for adoption and use in the management of Macrotermes species.

scholarly journals Dipole patterns in tropical precipitation were pervasive across landmasses throughout Marine Isotope Stage 5

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Katrina Nilsson-Kerr ◽  
Pallavi Anand ◽  
Philip B. Holden ◽  
Steven C. Clemens ◽  
Melanie J. Leng
Keyword(s):  
Large Scale ◽  
Marine Isotope Stage ◽  
Convergence Zone ◽  
Inter Tropical Convergence Zone ◽  
Tropical Regions ◽  
Tropical Precipitation ◽  
Rainfall Patterns ◽  
Marine Isotope Stage 5 ◽  
Climate Cooling ◽  
The Tropics

AbstractMost of Earth’s rain falls in the tropics, often in highly seasonal monsoon rains, which are thought to be coupled to the inter-hemispheric migrations of the Inter-Tropical Convergence Zone in response to the seasonal cycle of insolation. Yet characterization of tropical rainfall behaviour in the geologic past is poor. Here we combine new and existing hydroclimate records from six large-scale tropical regions with fully independent model-based rainfall reconstructions across the last interval of sustained warmth and ensuing climate cooling between 130 to 70 thousand years ago (Marine Isotope Stage 5). Our data-model approach reveals large-scale heterogeneous rainfall patterns in response to changes in climate. We note pervasive dipole-like tropical precipitation patterns, as well as different loci of precipitation throughout Marine Isotope Stage 5 than recorded in the Holocene. These rainfall patterns cannot be solely attributed to meridional shifts in the Inter-Tropical Convergence Zone.

scholarly journals Heat Stress and Goat Welfare: Adaptation and Production Considerations

Animals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1021
Author(s):  
Veerasamy Sejian ◽  
Mullakkalparambil V. Silpa ◽  
Mini R. Reshma Nair ◽  
Chinnasamy Devaraj ◽  
Govindan Krishnan ◽  
...  
Keyword(s):  
Heat Stress ◽  
Body Condition Score ◽  
Heat Exposure ◽  
Stocking Density ◽  
Production Performance ◽  
Farm Animals ◽  
Meat Production ◽  
Important Species ◽  
Tropical Regions ◽  
Tropical Climates

This review attempted to collate and synthesize information on goat welfare and production constraints during heat stress exposure. Among the farm animals, goats arguably are considered the best-suited animals to survive in tropical climates. Heat stress was found to negatively influence growth, milk and meat production and compromised the immune response, thereby significantly reducing goats’ welfare under extensive conditions and transportation. Although considered extremely adapted to tropical climates, their production can be compromised to cope with heat stress. Therefore, information on goat adaptation and production performance during heat exposure could help assess their welfare. Such information would be valuable as the farming communities are often struggling in their efforts to assess animal welfare, especially in tropical regions. Broadly three aspects must be considered to ensure appropriate welfare in goats, and these include (i) housing and environment; (ii) breeding and genetics and (iii) handling and transport. Apart from these, there are a few other negative welfare factors in goat rearing, which differ across the production system being followed. Such negative practices are predominant in extensive systems and include nutritional stress, limited supply of good quality water, climatic extremes, parasitic infestation and lameness, culminating in low production, reproduction and high mortality rates. Broadly two types of methodologies are available to assess welfare in goats in these systems: (i) animal-based measures include behavioral measurements, health and production records and disease symptoms; (ii) resources based and management-based measures include stocking density, manpower, housing conditions and health plans. Goat welfare could be assessed based on several indicators covering behavioral, physical, physiological and productive responses. The important indicators of goat welfare include agonistic behavior, vocalization, skin temperature, body condition score (BCS), hair coat conditions, rectal temperature, respiration rate, heart rate, sweating, reduced growth, reduced milk production and reduced reproductive efficiency. There are also different approaches available by which the welfare of goats could be assessed, such as naturalistic, functional and subjective approaches. Thus, assessing welfare in goats at every production stage is a prerequisite for ensuring appropriate production in this all-important species to guarantee optimum returns to the marginal and subsistence farmers.

scholarly journals Dynamics of invasive alien plant species in China under climate change scenarios

2021 ◽  
Vol 129 ◽  
pp. 107919
Author(s):  
Wenqin Tu ◽  
Qinli Xiong ◽  
Xiaoping Qiu ◽  
Yongmei Zhang
Keyword(s):  
Climate Change ◽  
Plant Species ◽  
Climate Change Scenarios ◽  
Alien Plant Species ◽  
Alien Plant ◽  
Invasive Alien Plant

scholarly journals Evaluating the role of contracting and expanding rainforest in initiating cycles of speciation across the Isthmus of Panama

2012 ◽  
Vol 279 (1742) ◽  
pp. 3520-3526 ◽  
Author(s):  
Brian Tilston Smith ◽  
Amei Amei ◽  
John Klicka
Keyword(s):  
Bird Species ◽  
Tropical Regions ◽  
Isthmus Of Panama ◽  
Species Pairs ◽  
The Matrix ◽  
High Species Richness ◽  
The Rich ◽  
The Tropics ◽  
The Impact

Climatic and geological changes across time are presumed to have shaped the rich biodiversity of tropical regions. However, the impact climatic drying and subsequent tropical rainforest contraction had on speciation has been controversial because of inconsistent palaeoecological and genetic data. Despite the strong interest in examining the role of climatic change on speciation in the Neotropics there has been few comparative studies, particularly, those that include non-rainforest taxa. We used bird species that inhabit humid or dry habitats that dispersed across the Panamanian Isthmus to characterize temporal and spatial patterns of speciation across this barrier. Here, we show that these two assemblages of birds exhibit temporally different speciation time patterns that supports multiple cycles of speciation. Evidence for these cycles is further corroborated by the finding that both assemblages consist of ‘young’ and ‘old’ species, despite dry habitat species pairs being geographically more distant than pairs of humid habitat species. The matrix of humid and dry habitats in the tropics not only allows for the maintenance of high species richness, but additionally this study suggests that these environments may have promoted speciation. We conclude that differentially expanding and contracting distributions of dry and humid habitats was probably an important contributor to speciation in the tropics.

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