Population genetics of hydrophilous angiosperms

Laushman, Roger H.

doi:10.1016/0304-3770(93)90069-9

Cited by 77 publications

(50 citation statements)

References 19 publications

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“…However, hydrophiles appear to have reasonably high levels of diversity compared to flowering plant species generally, although they commonly have lower P, H and H1 but higher GST values. There are only a few studies directly comparable to this one among hydrophiles, with two on seagrass (Zostera marina, Laushman, 1993;Amphibohs antarctica, Waycott et a!., 1996). The results presented here are for a widely distributed, hermaphrodite seagrass and show that P australis is genetically diverse (allozyme analysis) like the monoecious Z. marina, whereas the dioecious A. antarctica is genetically uniform for allozyme and M13DNA fingerprint analysis.…”

Section: Discussionmentioning

confidence: 96%

“…Recently, a few thorough investigations of genetic variability in hydrophilous angiosperms have demonstrated significant diversity in both the level and distribution of genetic variation. Species such as Ceratophyllum echinatum are predominantly clonal with little variation (Les, 1991), whereas others such as Zostera marina have genetically variable populations comprising many individuals (Laushman, 1993). Several other studies on hydrophiles have investigated the fine-scale genetic structure of populations, documenting both multiclonal (Les, 1991;Laushman, 1993;Alberte et at., 1994;Lokker et at., 1994;Waycott, 1995) and apparently uniclonal (Les, 1991; Correspondence and present address: Department of Tropical Environment Studies and Geography, James loads (Orth & Moore, 1983;Cambridge & McComb, 1984;Walker & McComb, 1992), increasing attention has been devoted to understanding the ecology and physiology of these organisms.…”

Section: Introductionmentioning

confidence: 99%

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Genetic variation within and between populations of Posidonia australis, a hydrophilous, clonal seagrass

1997

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Allozyme diversity was surveyed at 15 loci across 22 populations of the hydrophilous seagrass Posidonia australis (Hook. f.). Substantial genetic variation was detected (HT = 0.311) with a high proportion of this variation partitioned between populations (GST = 0.623). The high value of GST is attributed to large geographical distances between many of the populations and several of the extreme north-western populations having fixed homozygous genotypes. Southwestern populations of P australis were the most variable and these correlate with the highest species diversity in this genus. Intermediate levels of genetic diversity are observed in P australis when compared with other hydrophilous angiosperms. Average gene diversity values for hydrophilous taxa surveyed to date indicate lower HT and higher GST values than an average reported for 468 plant taxa. Patterns of genetic variability in different regions of the distribution of P australis may reflect past evolutionary diversification into novel environments and subsequent dispersal following the rifting of Australia from Antarctica in the early Tertiary.

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Section: Discussionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Genetic variation within and between populations of Posidonia australis, a hydrophilous, clonal seagrass

1997

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“…Sexual reproduction, however, is thought to be constrained because of hydrophilous pollination of flowers, limited dispersal of pollen and seeds, limited outcrossing rates associated with extensive clonal growth, and low survivorship of seeds and seedlings (Les 1988, Laushman 1993, Hemminga & Duarte 2000, Reusch 2001b). This life-history bottleneck, in combination with extensive clonal (vegetative) growth, led to the prediction that seagrass meadows would harbor low clonal diversity and be strongly structured with little gene flow (Les 1988, Barrett et al 1993, Hemminga & Duarte 2000.…”

Section: Introductionmentioning

confidence: 99%

Population genetics of dwarf eelgrass Zostera noltii throughout its biogeographic range

Coyer¹,

Diekmann²,

Serrão³

et al. 2004

Mar. Ecol. Prog. Ser.

100

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The marine angiosperm Zostera noltii (dwarf eelgrass), an important facilitator species and food source for invertebrates and waterfowl, predominantly inhabits intertidal habitats along eastern Atlantic shores from Mauritania to southern Norway/Kattegat Sea and throughout the Mediterranean, Black and Azov seas. We used 9 microsatellite loci to characterize population structure at a variety of spatial scales among 33 populations from 11 localities throughout the entire biogeographic range. Isolation by distance analysis suggested a panmictic genetic neighborhood of 100 to 150 km. At the global scale, a neighbor-joining tree based on Reynolds distances revealed strongly-supported groups corresponding to northern Europe, Mauritania and the Black/Azov Sea; separate Mediterranean and Atlantic-Iberian groups were poorly supported. Clones (genets with multiple ramets) were present in most populations but were generally small (ca. < 3 m 2 ). Exceptions were found in Mauritania (ca. 29 m in length), the Azov Sea (ca. 40 m in length) and the Black Sea (ca. 50 m in length). Although genetic diversity and allelic richness generally decreased from Mauritania to Denmark, the putative post-glacial recolonization route, both were unexpectedly high among populations from the German Wadden Sea.

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“…Female-dominated sex ratios are often documented among apomicts and thus apomixis cannot be discounted among seagrasses, particularly where genetic variability is low (Richards, 1986;Les, 1988;Asker & Jerling, 1992). The few published studies of genetic variability in seagrass populations have led to conflicting generalizations about their genetic diversity and recruitment methods (McMillan, 1982(McMillan, , 1991Les, 1988;Fain et a!., 1992;Laushman, 1993;Alberte et a!., 1994;Waycott, 1995). Most of these studies have been conducted on monoecious and hermaphrodite seagrasses, principally the northern hemisphere species Zostera marina, using allozymes (Gagnon et a!., 1980;Laushman, 1993), RFLPs (Fain et a!., 1992) and DNA fingerprinting (Alberte et al, 1994).…”

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confidence: 99%

Genetic uniformity in Amphibolis antarctica, a dioecious seagrass

1996

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Few detailed studies have been published on genetic variation in seagrasses except those on the monoecious Zostera marina L. or the hermaphrodite Posidonia australis Hook. f This paper presents allozyme, RFLP and reproductive biology data on Amphibolis antarctica (Labill.) Sonder & Aschers, one of the 75 per cent of all seagrass species which are dioecious.Collections were made from approximately one-third of the species range in Western Australia. Its only congener, A. gnfflthii (J. M. Black) den Hartog, was collected from one site to provide a comparison. Flowering was observed in 25 per cent of the shoots surveyed and the average sex ratio was 3.8: 1 (F:M) which it has been suggested indicates sexual reproduction. No genetic variation was found within or between populations at 14 allozyme loci. 18S RFLPs and M13 DNA fingerprinting gave few satisfactory results but also did not exhibit any variability. Allozyme variation was observed between A. antarctica and A. griffithii, the only congeneric species. The lack of allozyme and DNA variation within A. antarctica indicates a potentially low level of outbreeding, a highly clonal reproductive system or a very efficient genetic system in A. antarctica. The hypothesis that the dioecious reproductive system evolved in seagrasses to maximize outbreeding and genetic variability, proposed by several authors, is questioned in light of these data.

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Population genetics of hydrophilous angiosperms

Cited by 77 publications

References 19 publications

Genetic variation within and between populations of Posidonia australis, a hydrophilous, clonal seagrass

Genetic variation within and between populations of Posidonia australis, a hydrophilous, clonal seagrass

Population genetics of dwarf eelgrass Zostera noltii throughout its biogeographic range

Genetic uniformity in Amphibolis antarctica, a dioecious seagrass

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