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- Breed, Martin F., et al.
(författare)
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Mating system and early viability resistance to habitat fragmentation in a bird-pollinated eucalypt
- 2015
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Ingår i: Heredity. - : Springer Science and Business Media LLC. - 0018-067X .- 1365-2540. ; 115:2, s. 100-107
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Tidskriftsartikel (refereegranskat)abstract
- Habitat fragmentation has been shown to disrupt ecosystem processes such as plant-pollinator mutualisms. Consequently, mating patterns in remnant tree populations are expected to shift towards increased inbreeding and reduced pollen diversity, with fitness consequences for future generations. However, mating patterns and phenotypic assessments of open-pollinated progeny have rarely been combined in a single study. Here, we collected seeds from 37 Eucalyptus incrassata trees from contrasting stand densities following recent clearance in a single South Australian population (intact woodland = 12.6 trees ha(-1); isolated pasture = 1.7 trees ha(-1); population area = 10 km(2)). 649 progeny from these trees were genotyped at eight microsatellite loci. We estimated genetic diversity, spatial genetic structure, indirect contemporary pollen flow and mating patterns for adults older than the clearance events and open-pollinated progeny sired post-clearance. A proxy of early stage progeny viability was assessed in a common garden experiment. Density had no impact on mating patterns, adult and progeny genetic diversity or progeny growth, but was associated with increased mean pollen dispersal. Weak spatial genetic structure among adults suggests high historical gene flow. We observed preliminary evidence for inbreeding depression related to stress caused by fungal infection, but which was not associated with density. Higher observed heterozygosities in adults compared with progeny may relate to weak selection on progeny and lifetime-accumulated mortality of inbred adults. E. incrassata appears to be resistant to the negative mating pattern and fitness changes expected within fragmented landscapes. This pattern is likely explained by strong outcrossing and regular long-distance pollen flow.
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- Breed, Martin F., et al.
(författare)
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Mating patterns and pollinator mobility are critical traits in forest fragmentation genetics
- 2015
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Ingår i: Heredity. - : Springer Science and Business Media LLC. - 0018-067X .- 1365-2540. ; 115:2, s. 108-114
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Tidskriftsartikel (refereegranskat)abstract
- Most woody plants are animal-pollinated, but the global problem of habitat fragmentation is changing the pollination dynamics. Consequently, the genetic diversity and fitness of the progeny of animal-pollinated woody plants sired in fragmented landscapes tend to decline due to shifts in plant-mating patterns (for example, reduced outcrossing rate, pollen diversity). However, the magnitude of this mating-pattern shift should theoretically be a function of pollinator mobility. We first test this hypothesis by exploring the mating patterns of three ecologically divergent eucalypts sampled across a habitat fragmentation gradient in southern Australia. We demonstrate increased selfing and decreased pollen diversity with increased fragmentation for two small-insect-pollinated eucalypts, but no such relationship for the mobile-bird-pollinated eucalypt. In a meta-analysis, we then show that fragmentation generally does increase selfing rates and decrease pollen diversity, and that more mobile pollinators tended to dampen these mating-pattern shifts. Together, our findings support the premise that variation in pollinator form contributes to the diversity of mating-pattern responses to habitat fragmentation.
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- Breed, Martin, 1981-, et al.
(författare)
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Shifts in reproductive assurance strategies and inbreeding costs associated with habitat fragmentation in Central American mahogany
- 2012
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 15:5, s. 444-452
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Tidskriftsartikel (refereegranskat)abstract
- The influence of habitat fragmentation on mating patterns and progeny fitness in trees is critical for understanding the long-term impact of contemporary landscape change on the sustainability of biodiversity. We examined the relationship between mating patterns, using microsatellites, and fitness of progeny, in a common garden trial, for the insect-pollinated big-leaf mahogany, Swietenia macrophylla King, sourced from forests and isolated trees in 16 populations across Central America. As expected, isolated trees had disrupted mating patterns and reduced fitness. However, for dry provenances, fitness was negatively related to correlated paternity, while for mesic provenances, fitness was correlated positively with outcrossing rate and negatively with correlated paternity. Poorer performance of mesic provenances is likely because of reduced effective pollen donor density due to poorer environmental suitability and greater disturbance history. Our results demonstrate a differential shift in reproductive assurance and inbreeding costs in mahogany, driven by exploitation history and contemporary landscape context.
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- Sijmons, R.H., et al.
(författare)
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Piebaldism in a mentally retarded girl with rare deletion of the long arm of chromosome 4
- 1993
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Ingår i: Pediatric Dermatology. - : Wiley. - 0736-8046 .- 1525-1470. ; 10:3, s. 235-239
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Tidskriftsartikel (refereegranskat)abstract
- A 4-year-old mentally retarded girl had congenital depigmentations of ventrolateral parts of the chest, abdomen, and legs. She also showed dysmorphic features of the head, thorax, and extremities, a pigmented ring in both irises, and a hernia of the left obliquus muscle. Cytogenetic investigations revealed deletion of chromosome 4 for the long arm segment q12-q21. The typical depigmentations, reported in four other patients with a similar chromosomal deletion, correspond with those in the autosomal dominant piebald trait. Mutations in the Kit protooncogene (mapped to the chromosome (4q11-4q12 region) have been found in patients affected with this dominant disorder. Piebaldism in children with developmental delay and dysmorphic features should alert the physician to the possibility of a deletion of the long arm of chromosome 4.
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- Bierla, Joanna B., et al.
(författare)
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Sperm morphology of the Eurasian beaver, Castor fiber: An example of a species of rodent with highly derived and pleiomorphic sperm populations
- 2007
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Ingår i: Journal of morphology. - : Wiley-Blackwell. - 0362-2525 .- 1097-4687. ; 268:8, s. 683-689
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Tidskriftsartikel (refereegranskat)abstract
- The structural organization of the spermatozoon from the Eurasian beaver, Castor fiber (Family: Castoridae), was determined and compared to that of other sciuromorph rodents. The beaver spermatozoon has a head, which is variable in form but usually paddle-shaped, with a small nucleus and very large acrosome, and a tail that is relatively short compared to that of most other rodents. Transmission electron microscopy indicates that in most testicular spermatozoa the acrosome projects apically, although in a few it becomes partly flexed. During the final stages of maturation, however, the acrosome becomes highly folded so that the apical segment comes to lie alongside part of the acrosome that occurs lateral to the nucleus, with, in some cases, fusion taking place between the outer acrosomal membranes. The sperm nucleus is wedge-shaped, being broader basally and narrowing apically with an occasional large nuclear vacuole occurring. This spermatozoon structure is markedly different from that found in the other species of Geomyoidea, which is the sister group of the Castoridae. The findings thus emphasize the highly divergent nature of the beaver spermatozoon and demonstrate that, within the proposed Infraorder Castorimorpha, very large differences in sperm structure have evolved.
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- Breed, Martin F., 1981-, et al.
(författare)
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Clarifying climate change adaptation responses for scattered trees in modified landscapes
- 2011
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 48:3, s. 637-641
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Tidskriftsartikel (refereegranskat)abstract
- 1. Many studies have investigated adaptation to climate change. However, the term ‘adaptation’ has been used ambiguously and sometimes included parts of both classic evolutionary processes and conservation planning measures (i.e. human-mediated adaptation).2. To reduce ambiguity, we define three classes of evolutionary processes involved in adaptation – migrational, novel-variant and plasticity. Migrational adaptation describes the process of redistribution of standing genetic variation among populations. Novel-variant adaptation describes the increase in frequency of beneficial, new genetic variants. Plasticity adaptation refers to adaptive plastic responses of organisms to environmental stressors. Quite separately, human-mediated adaptation aims to maintain these evolutionary processes.3. Whilst the role of scattered trees in migrational adaptation of fauna may have been neglected in the past, their capacity to assist migrational adaptation of trees has been previously documented. However, their role in novel-variant and plasticity adaptation is generally unrecognised, and warrants further attention.4. Synthesis and applications. By defining different aspects of adaptation carefully, we show that scattered trees should not be cleared since they may facilitate gene flow across fragmented landscapes. However, they should be avoided as dominant seed sources since their stock may be of poor quality.
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| 9. |
- Breed, Martin F., 1981-, et al.
(författare)
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Which provenance and where? : Seed sourcing strategies for revegetation in a changing environment
- 2013
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Ingår i: Conservation Genetics. - : Springer Science and Business Media LLC. - 1566-0621 .- 1572-9737. ; 14:1, s. 1-10
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Forskningsöversikt (refereegranskat)abstract
- Revegetation is one practical application of science that should ideally aim to combine ecology with evolution to maximise biodiversity and ecosystem outcomes. The strict use of locally sourced seed in revegetation programs is widespread and is based on the expectation that populations are locally adapted. This practice does not fully integrate two global drivers of ecosystem change and biodiversity loss: habitat fragmentation and climate change. Here, we suggest amendments to existing strategies combined with a review of alternative seed-sourcing strategies that propose to mitigate against these drivers. We present a provenancing selection guide based on confidence surrounding climate change distribution modelling and data on population genetic and/or environmental differences between populations. Revegetation practices will benefit from greater integration of current scientific developments and establishment of more long-term experiments is key to improving the long-term success. The rapid growth in carbon and biodiversity markets creates a favourable economic climate to achieve these outcomes.
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| 10. |
- Breed, Martin, 1981-, et al.
(författare)
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Pollen diversity matters : revealing the neglected effect of pollen diversity on fitness in fragmented landscapes
- 2012
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Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 21:24, s. 5955-5968
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Tidskriftsartikel (refereegranskat)abstract
- Few studies have documented the impacts of habitat fragmentation on plant mating patterns together with fitness. Yet, these processes require urgent attention to better understand the impact of contemporary landscape change on biodiversity and for guiding native plant genetic resource management. We examined these relationships using the predominantly insect-pollinated Eucalyptus socialis. Progeny were collected from trees located in three increasingly disturbed landscapes in southern Australia and were planted out in common garden experiments. We show that individual mating patterns were increasingly impacted by lower conspecific density caused by habitat fragmentation. We determined that reduced pollen diversity probably has effects over and above those of inbreeding on progeny fitness. This provides an alternative mechanistic explanation for the indirect density dependence often inferred between conspecific density and offspring fitness.
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