scholarly journals Long-distance dispersal of pigeons and doves generated new ecological opportunities for host-switching and adaptive radiation by their parasites

2021 ◽  
Author(s):  
Bret M Boyd ◽  
Nam-Phuong Nguyen ◽  
Julie M Allen ◽  
Robert M Waterhouse ◽  
Kyle B Vo ◽  
...  
Keyword(s):  
Body Size ◽  
Adaptive Radiation ◽  
Host Species ◽  
Dominant Mode ◽  
Host Switching ◽  
Long Distance Dispersal ◽  
Long Distance ◽  
Ideal System ◽  
Adaptive Radiations ◽  
Over Time

Adaptive radiation is an important mechanism of organismal diversification, and can be triggered by new ecological opportunities. Although poorly studied in this regard, parasites present an ideal system to study adaptive radiations because of their close associations with host species. Both experimental and comparative studies suggest that the ectoparasitic wing lice of pigeons and doves have undergone an adaptive radiation, resulting in differences in both body size and overall coloration. Here we show that long-distance dispersal by dove hosts was important for parasite diversification, providing new ecological opportunities for parasites to speciate by host-switching. We further show that these new opportunities for host-switching decreased over time, and cospeciation became the more dominant mode of parasite speciation. Taken together, our results suggest that host dispersal, followed by host-switching, provided novel ecological opportunities that facilitated adaptive radiation by parasites.

Morphological, evolutionary and taxonomic aspects of Australian and New Zealand Microseris (Asteraceae)

2002 ◽  
Vol 50 (1) ◽  
pp. 127 ◽  
Author(s):  
Kitty Vijverberg ◽  
Louis Lie ◽  
Konrad Bachmann
Keyword(s):  
New Zealand ◽  
Adaptive Radiation ◽  
Present Species ◽  
Western North America ◽  
Long Distance Dispersal ◽  
Long Distance ◽  
Unique Event ◽  
Plant Group ◽  
Show Evidence ◽  
Recent Occurrence

The Australian and New Zealand Microseris is supposed to have evolved from one or a few diaspores after a unique event of long-distance dispersal from western North America. At present, the plant group includes two species, M. lanceolata (Walp.) Sch.-Bip. and M. scapigera (Forst.) Sch.-Bip., each with two morphologically and ecologically divergent ecotypes. In spite of this classification, the morphological variation within and among ecotypes is not entirely consistent, and molecular investigations show evidence for the, possibly recent, occurrence of hybridisations between plants of different ecotypes. The present study investigates the overall morphological similarities among 1–4 plants of each of 54 Australian and New Zealand Microseris populations. The aim of the study was to gain further insights into the delimitation of species and ecotypes, the placement of populations that could thus far not be assigned to an ecotype and the adaptive radiation of the plant group. The results confirm the previously defined ecotypes and assign all but two of the questionable populations to ecotypes. They show that a broad range of character states rather than a few 'diagnostic' ones are specific for the ecotypes. The data confirm our earlier conclusion from molecular results, indicating that ecotype characteristics are maintained or reestablished by selection or adaptation, after dispersal or hybridisation between ecotypes. Despite (incidental) genetic exchange among populations of different ecotypes, the process of adaptive radiation is progressing. The combined morphological and molecular results are not incongruent with the present species delimitation. However, they also may support the split up of M. scapigera into two species and other phylogenetic solutions.

Longevity of light- and dark-colored basidiospores from saprotrophic mushroom-forming fungi

Mycologia ◽  
2018 ◽  
Vol 110 (1) ◽  
pp. 131-135 ◽  
Author(s):  
Nguyen
Keyword(s):  
Ectomycorrhizal Fungi ◽  
The Other ◽  
Optimal Conditions ◽  
Long Distance Dispersal ◽  
Ecological Strategies ◽  
Long Distance ◽  
Extended Longevity ◽  
Spore Longevity ◽  
Over Time ◽  
Basidiomycete Fungi

Fungi can produce resistant propagules that may last for decades. Basidiospores from ectomycorrhizal fungi had been experimentally shown to last for at least 6 yr, but there are few reports on the longevity of saprotrophic members of mushroom-forming fungi. Here, the author shows evidence of spore longevity of these fungi by collecting, drying, storing, and germinating these spores over time. Results showed that dark-colored spores have a much-extended longevity as compared to light-colored spores. Dark-colored spores of some species are viable to at least 2.8 yr, whereas light-colored spores are generally viable for a much shorter period of time. The author proposes that mushroom-forming basidiomycete fungi employ two different ecological strategies: one with extended longevity that allows for long-distance dispersal, and the other takes advantage of optimal conditions that support both mushroom formation, basidiospore dispersal, and germination locally.

scholarly journals Road Maintenance in Africa: Approaches and Perspectives

2018 ◽  
Vol 38 ◽  
pp. 01005
Author(s):  
Mostafa Hassan M
Keyword(s):  
Rural Communities ◽  
Dominant Mode ◽  
Poor Health ◽  
Operating Costs ◽  
Road Maintenance ◽  
Significant Progress ◽  
African Countries ◽  
Institutional Reforms ◽  
Similarities And Differences ◽  
Over Time

In Africa, roads are the dominant mode of passenger and freight transport, for which the need is growing rapidly. It is noticeable that most of the African countries do not do enough to ensure the sustainability of road infrastructure as it has been widely reported that roads are affected, to varying degrees, by premature deterioration. Most of the African countries have adopted institutional reforms, notably entailing the creation of road funds and road agencies, and made significant progress on road maintenance. However, many challenges remain to be addressed in all of them to ensure appropriate maintenance. Although spending on road maintenance has increased over time in all African countries it remains insufficient to cover the needs. Poorly maintained roads constrain mobility, significantly raise vehicle operating costs, increase accident rates and their associated human and property costs, and aggravate isolation, poverty, poor health, and illiteracy in rural communities. This paper focuses, in particular, on road maintenance in some African countries considering types of road maintenance and the different approaches aiming at a comparison to reflect on similarities and differences.

scholarly journals PSVIII-17 Assessment of conformational changes across three parities in sows

2020 ◽  
Vol 98 (Supplement_3) ◽  
pp. 221-222
Author(s):  
Melanie D Trenhaile-Grannemann ◽  
Ronald M Lewis ◽  
Stephen D Kachman ◽  
Kenneth J Stalder ◽  
Benny E Mote
Keyword(s):  
Body Size ◽  
Body Length ◽  
Conformational Changes ◽  
Repeated Measures ◽  
Fixed Effects ◽  
Random Effect ◽  
Joint Angles ◽  
Body Depth ◽  
Conformation Changes ◽  
Over Time

Abstract Conformation-based sow selection is performed prior to reaching mature size, yet little is known about how conformation changes as growth continues. To assess conformation changes, 9 conformational traits were objectively measured at 12 discrete time points between 112 d of age and parity 3 weaning on 622 sows in 5 cohorts. The 9 traits included 5 body size traits (body length, body depth at the shoulder and flank, and height at the shoulder and flank) and 4 joint angles (knee, hock, and front and rear pastern). Data were analyzed with a repeated measures model (SAS V 9.4) including cohort and time point as fixed effects, sire as a random effect, and heterogeneous compound symmetry as the covariance structure. Sire variance ranged from 0.16 (body depth shoulder) to 2.00 (body length) cm2 for body size traits and 2.28 (rear pastern) to 4.22 (front pastern) degrees2 for joint angles. Cohort had an effect on all traits (P < 0.05). All traits displayed changes over time (P < 0.001). Size traits increased between 112 d of age and parity 3 weaning (64.16 vs. 107.57 cm, 26.62 vs. 44.14 cm, 23.32 vs. 36.92 cm, 46.10 vs. 73.55 cm, 49.36 vs. 77.47 cm for body length, body depth shoulder and flank, and height shoulder and flank, respectively); however, they fluctuated within parity by increasing during gestation and decreasing at weaning. Knee angle decreased (164.12 vs. 150.72 degrees) while fluctuating within parity by decreasing in the second half of gestation and increasing after weaning. Front and rear pastern angles decreased over time (60.89 vs. 53.74 degrees and 64.64 vs. 55.50 degrees for front and rear pastern, respectively), while biologically negligible change was observed in hock angle (148.63 vs. 147.48 degrees). Sow conformation changes throughout life, and these changes may require consideration when making selection decisions.

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