Biodiversity hotspots and Ocbil theory

Hopper, Stephen D.; Silveira, Fernando A. O.; Fiedler, Peggy L.

doi:10.1007/s11104-015-2764-2

Cited by 162 publications

(155 citation statements)

References 362 publications

(437 reference statements)

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“…Ultimately, extreme longevity combined with the genetic consequences of wide outcrossing as a result of bird pollination are likely to be important for the persistence of genetic variation in small, geographically isolated stands of E. caesia. This conclusion is in accordance with the James Effect Hypothesis (Hopper, 2009;Hopper et al, 2016) that predicts that mechanisms conserving heterozygosity will feature prominently in rare, localised endemics, as a result of prolonged genetic isolation.…”

Section: Discussionsupporting

confidence: 88%

Paternity analysis reveals wide pollen dispersal and high multiple paternity in a small isolated population of the bird-pollinated Eucalyptus caesia (Myrtaceae)

et al. 2016

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Optimal foraging behaviour by nectavores is expected to result in a leptokurtic pollen dispersal distribution and predominantly near-neighbour mating. However, complex social interactions among nectarivorous birds may result in different mating patterns to those typically observed in insect-pollinated plants. Mating system, realised pollen dispersal and spatial genetic structure were examined in the bird-pollinated Eucalyptus caesia, a species characterised by small, geographically disjunct populations. Nine microsatellite markers were used to genotype an entire adult stand and 181 seeds from 28 capsules collected from 6 trees. Mating system analysis using MLTR revealed moderate to high outcrossing (t m = 0.479-0.806) and low estimates of correlated paternity (r p = 0.136 ± s.e. 0.048). Paternity analysis revealed high outcrossing rates (mean = 0.72) and high multiple paternity, with 64 different sires identified for 181 seeds. There was a significant negative relationship between the frequency of outcross mating and distance between mating pairs. Realised mating events were more frequent than expected with random mating for plants o40 m apart. The overall distribution of pollen dispersal distances was platykurtic. Despite extensive pollen dispersal within the stand, three genetic clusters were detected by STRUCTURE analysis. These genetic clusters were strongly differentiated yet geographically interspersed, hypothesised to be a consequence of rare recruitment events coupled with extreme longevity. We suggest that extensive polyandry and pollen dispersal is a consequence of pollination by highly mobile honeyeaters and may buffer E. caesia against the loss of genetic diversity predicted for small and genetically isolated populations.

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Section: Discussionsupporting

confidence: 88%

Paternity analysis reveals wide pollen dispersal and high multiple paternity in a small isolated population of the bird-pollinated Eucalyptus caesia (Myrtaceae)

et al. 2016

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“…High levels of endemism can result from two scenarios: either (a) these environments promote high local speciation (neoendemisms), or (b) they permit survival of lineages that undergo extinction elsewhere (palaeoendemisms) (Keppel et al, ). Even though campo rupestre have been classified as an old, climatically buffered and infertile landscape (Conceição et al, ; Hopper, Silveira, & Fiedler, ), thus intuitively associating them to palaeoendemisms, phylogenies of some endemic lineages have shown that recent, fast speciation is surprisingly common (e.g., Antonelli, Verola, Parisod, & Gustafsson, ; Ribeiro, Rapini, Damascena, & Berg, ; Rando et al, ). There is certainly scope for further investigation on this question and we strongly believe that officializing these bioregions is going to facilitate such studies.…”

Section: Discussionmentioning

confidence: 99%

Outstanding plant endemism levels strongly support the recognition ofcampo rupestreprovinces in mountaintops of eastern South America

Colli‐Silva

Vasconcelos

Pirani

2019

Journal of Biogeography

104

100

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Aim The Brazilian campo rupestre is a vegetation associated to ancient mountaintops in eastern South America, spread mainly over disjunct areas of the Espinhaço Range and the Chapada dos Veadeiros. These areas hold outstanding levels of plant diversity and endemism, but despite their uniqueness they have been neglected in recent bioregionalizations for the Neotropical region. Given their particular levels of species richness and endemism, we here test the recognition of these as distinct bioregions within the Chacoan dominion. Location Mountaintops of eastern South America. Methods We listed 1,748 angiosperm species endemic to the campo rupestre of the Espinhaço Range and Chapada dos Veadeiros regions, based on the data gathered from the Brazilian Flora 2020 Project. We extracted all occurrence information available from GBIF (the Global Biodiversity Information Facility) for such list and also for a polygon gathering all the study area, including information from adjacent vegetations. Data went through standard cleaning procedures and a network clustering analysis was performed to delimitate the boundaries of the new bioregions. Results Our data strongly support the recognition of two distinct bioregions along the Espinhaço Range, but none in the Chapada dos Veadeiros. Given their high levels of endemism and singularity within the Chacoan dominion, we formalize two provinces associated to campo rupestre in the Espinhaço Range, naming them as “Chapada Diamantina” and “Southern Espinhaço” provinces. Within the latter province, three districts are also recognized, based on this and previous studies: “Diamantina Plateau”, “Grão‐Mogol” and “Iron Quadrangle” districts. Main conclusions The formalization of new and previously described bioregions highlights the campo rupestre as a vegetation harbouring outstanding levels of species richness and endemism in South America, contributing to a better understanding of biogeographical patterns in the Neotropics. Also, as we follow the International Code of Area Nomenclature as a device to standardize recognition of bioregions, this shall facilitate further biogeographical and conservation studies in these areas. Further assessments with new and revisited data are needed to enable minor scale bioregionalization within the Chacoan dominion.

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“…Eucalyptus caesia Benth., a long‐lived bird‐pollinated lignotuberous tree endemic on granite outcrops, is a well‐suited species to study patterns of genetic structure and connectivity of historically fragmented populations at a landscape scale (Bezemer et al, ; Byrne & Hopper, ; Moran & Hopper, ). Our study is located in the Southwest Australian Floristic Region (Hopper & Gioia, ), a global biodiversity hot spot with numerous examples of old, climatically buffered infertile landscapes (OCBILs) and, consequently, old plant lineages with complex evolutionary histories (Hopper, ; Hopper, Silveira, & Fiedler, ). Eucalyptus caesia populations have a scattered distribution in south‐western Australia with 25 known stands ranging in size from a single individual to several hundred plants based on aerial and on‐ground surveys (Hopper, Campbell, & Moran, ; present paper).…”

Section: Introductionmentioning

confidence: 99%

Conservation of old individual trees and small populations is integral to maintain species' genetic diversity of a historically fragmented woody perennial

et al. 2019

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Historically fragmented and specialized habitats such as granite outcrops are understudied globally unique hot spots of plant evolution. In contrast to predictions based on mainstream population genetic theory, some granite outcrop plants appear to have persisted as very small populations despite prolonged geographic and genetic isolation. Eucalyptus caesia Benth. is a long‐lived lignotuberous tree endemic with a naturally fragmented distribution on granite outcrops in south‐western Australia. To quantify population to landscape‐level genetic structure, we employed microsatellite genotyping at 14 loci of all plants in 18 stands of E. caesia. Sampled stands were characterized by low levels of genetic diversity, small absolute population sizes, localized clonality and strong fine‐scale genetic subdivision. There was no significant relationship between population size and levels of heterozygosity. At the landscape scale, high levels of population genetic differentiation were most pronounced among representatives of the two subspecies in E. caesia as originally circumscribed. Past genetic interconnection was evident between some geographic neighbours separated by up to 20 km. Paradoxically, other pairs of neighbouring stands as little as 7 km apart were genetically distinct. There was no consistent pattern of isolation by distance across the 280 km range of E. caesia. Low levels of gene flow, together with strong drift within stands, provide some explanation of the patterns of genetic differentiation we observed. Individual genet longevity via the ability to repeatedly resprout and expand from a lignotuber may enhance the persistence of some woody perennial endemic plants despite small population size, minimal genetic interconnection and low heterozygosity.

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Biodiversity hotspots and Ocbil theory

Cited by 162 publications

References 362 publications

Paternity analysis reveals wide pollen dispersal and high multiple paternity in a small isolated population of the bird-pollinated Eucalyptus caesia (Myrtaceae)

Paternity analysis reveals wide pollen dispersal and high multiple paternity in a small isolated population of the bird-pollinated Eucalyptus caesia (Myrtaceae)

Outstanding plant endemism levels strongly support the recognition ofcampo rupestreprovinces in mountaintops of eastern South America

Conservation of old individual trees and small populations is integral to maintain species' genetic diversity of a historically fragmented woody perennial

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