Quercus hinckleyi, commonly called Hinckley oak, is a rare species in the white oak group (Quercus Section Quercus). It has a restricted range in the Chihuahuan Desert of the southwestern United States and northern Mexico (Chihuahua and Coahuila).[2] In the US, it occurs in only two counties in southwestern Texas and is federally listed as a threatened species.[3]
Quercus hinckleyi is a shrub that forms a dense, tangled thicket no more than 1.5 metres (5 feet) tall. The highly branched stems are coated in scaly gray bark and the smaller twigs are brown and sometimes waxy. The leaves are up to 1.5 centimetres (5⁄8 inch) long by 1.5 cm wide and have large, widely spaced teeth, resembling holly leaves. The blades are leathery, waxy, and blue-green in color. The fruit is an acorn 1 to 1.5 cm wide at the cap, the nut measuring up to 2 cm (3⁄4 in) long.[4]
Hinckley oak is a relict species with a restricted distribution, but which was more common at the end of the last ice age.[6] Records from fossilized acorns and rodent middens show this species was prevalent until about 10,000 years ago.[7] However, as the climate of the region became warmer and drier, this species likely retreated, resulting in its current restricted range.[5][6]
Conservationedit
Hinckley oak is federally listed as a threatened species of the United States[3] and is listed as Critically Endangered by the IUCN Red List.[8] Postglacial climate change is believed to be the main reason for the limited distribution of the species.[3] Low rates of reproduction and poor regeneration may threaten the persistence of this rare oak.[7] High levels of clonal growth, or asexual reproduction, have been observed at small subpopulations, which have been found to contain as few as three genetically distinct individuals.[5]
Geneticsedit
As a rare species with small, isolated populations, Quercus hinckleyi was suspected to face extinction risk due to issues associated with low levels of genetic diversity.[3] However, a recent genetic analysis found that Hinckley oak displayed surprisingly high levels of genetic variability (based on allelic richness) and showed no evidence of inbreeding.[5] This study found the genetics of Q. hinckleyi to be on par with common widespread species of oaks, though high levels of cloning were reported. The plant's ability to reproduce asexually may be a successful strategy for persisting in small populations under a changing climate, though it may also hamper its ability to respond to future change.[5]
Hybridization with co-occurring common oaks is considered another threat to this species.[3] Recent genetic work examined whether Q. hinckleyi was in fact hybridizing with nearby oak species, Quercus pungens and Quercus vaseyana.[9] This analysis revealed that Hinckley oak and Q. pungens were hybridizing to a limited degree, but found no evidence of overwhelming genetic swamping, suggesting it is not a major conservation concern. In fact, hybridization has been suggested as one mechanism by which adaptive genetic diversity may be added into small populations of Hinckley oak.[9]
Referencesedit
^Beckman, E. (2017). "Quercus hinckleyi". IUCN Red List of Threatened Species. 2017: e.T30955A176953830. doi:10.2305/IUCN.UK.2017-2.RLTS.T30955A176953830.en. Retrieved 20 November 2021.
^ abcdeBacks, Janet Rizner; Terry, Martin; Klein, Mollie; Ashley, Mary V. (2015). "Genetic analysis of a rare isolated species: A tough little West Texas oak, Quercus hinckleyi C.H. Mull. 1". The Journal of the Torrey Botanical Society. 142 (4): 302–313. doi:10.3159/torrey-d-14-00091.1. S2CID 85807727.
^ abElias, Scott A.; Van Devender, Thomas R. (1990-09-01). "Fossil insect evidence for late Quaternary climatic change in the Big Bend region, Chihuahuan Desert, Texas". Quaternary Research. 34 (2): 249–261. Bibcode:1990QuRes..34..249E. doi:10.1016/0033-5894(90)90035-J. S2CID 140539014.
^Nixon, K.; et al. (1998). "Quercus hinckleyi". IUCN Red List of Threatened Species. doi:10.2305/iucn.uk.1998.rlts.t30955a9595490.en.
^ abBacks, Janet Rizner; Terry, Martin; Ashley, Mary V. (2016-01-05). "Using Genetic Analysis to Evaluate Hybridization as a Conservation Concern for the Threatened Species Quercus hinckleyi C.H. Muller (Fagaceae)". International Journal of Plant Sciences. 177 (2): 122–131. doi:10.1086/684177. ISSN 1058-5893. S2CID 88294300.
External linksedit
USDA Plants Profile for Quercus hinckleyi
Tropicos.org: Photo of herbarium specimen collected in Texas in 1950
December 18, 2023
quercus, hinckleyi, commonly, called, hinckley, rare, species, white, group, quercus, section, quercus, restricted, range, chihuahuan, desert, southwestern, united, states, northern, mexico, chihuahua, coahuila, occurs, only, counties, southwestern, texas, fed. Quercus hinckleyi commonly called Hinckley oak is a rare species in the white oak group Quercus Section Quercus It has a restricted range in the Chihuahuan Desert of the southwestern United States and northern Mexico Chihuahua and Coahuila 2 In the US it occurs in only two counties in southwestern Texas and is federally listed as a threatened species 3 Hinckley oakConservation statusCritically Endangered IUCN 3 1 1 Scientific classificationKingdom PlantaeClade TracheophytesClade AngiospermsClade EudicotsClade RosidsOrder FagalesFamily FagaceaeGenus QuercusSubgenus Quercus subg QuercusSection Quercus sect QuercusSpecies Q hinckleyiBinomial nameQuercus hinckleyiC H Mull Contents 1 Description 2 Distribution and ecology 3 Conservation 3 1 Genetics 4 References 5 External linksDescription editQuercus hinckleyi is a shrub that forms a dense tangled thicket no more than 1 5 metres 5 feet tall The highly branched stems are coated in scaly gray bark and the smaller twigs are brown and sometimes waxy The leaves are up to 1 5 centimetres 5 8 inch long by 1 5 cm wide and have large widely spaced teeth resembling holly leaves The blades are leathery waxy and blue green in color The fruit is an acorn 1 to 1 5 cm wide at the cap the nut measuring up to 2 cm 3 4 in long 4 Distribution and ecology editQuercus hinckleyi is known from just a few occurrences in Brewster and Presidio counties in West Texas most of which occur in Big Bend Ranch State Park 3 It has also been recorded from Mexico 2 4 though the extent of its distribution there remains unknown 5 It grows in Chihuahuan Desert scrub habitat on dry desert slopes and rocky limestone soils 3 4 Hinckley oak is a relict species with a restricted distribution but which was more common at the end of the last ice age 6 Records from fossilized acorns and rodent middens show this species was prevalent until about 10 000 years ago 7 However as the climate of the region became warmer and drier this species likely retreated resulting in its current restricted range 5 6 Conservation editHinckley oak is federally listed as a threatened species of the United States 3 and is listed as Critically Endangered by the IUCN Red List 8 Postglacial climate change is believed to be the main reason for the limited distribution of the species 3 Low rates of reproduction and poor regeneration may threaten the persistence of this rare oak 7 High levels of clonal growth or asexual reproduction have been observed at small subpopulations which have been found to contain as few as three genetically distinct individuals 5 Genetics edit As a rare species with small isolated populations Quercus hinckleyi was suspected to face extinction risk due to issues associated with low levels of genetic diversity 3 However a recent genetic analysis found that Hinckley oak displayed surprisingly high levels of genetic variability based on allelic richness and showed no evidence of inbreeding 5 This study found the genetics of Q hinckleyi to be on par with common widespread species of oaks though high levels of cloning were reported The plant s ability to reproduce asexually may be a successful strategy for persisting in small populations under a changing climate though it may also hamper its ability to respond to future change 5 Hybridization with co occurring common oaks is considered another threat to this species 3 Recent genetic work examined whether Q hinckleyi was in fact hybridizing with nearby oak species Quercus pungens and Quercus vaseyana 9 This analysis revealed that Hinckley oak and Q pungens were hybridizing to a limited degree but found no evidence of overwhelming genetic swamping suggesting it is not a major conservation concern In fact hybridization has been suggested as one mechanism by which adaptive genetic diversity may be added into small populations of Hinckley oak 9 References edit Beckman E 2017 Quercus hinckleyi IUCN Red List of Threatened Species 2017 e T30955A176953830 doi 10 2305 IUCN UK 2017 2 RLTS T30955A176953830 en Retrieved 20 November 2021 a b Quercus hinckleyi The Nature Conservancy a b c d e f g USFWS Quercus hinckleyi Five year Review September 2009 a b c Quercus hinckleyi Flora of North America a b c d e Backs Janet Rizner Terry Martin Klein Mollie Ashley Mary V 2015 Genetic analysis of a rare isolated species A tough little West Texas oak Quercus hinckleyi C H Mull 1 The Journal of the Torrey Botanical Society 142 4 302 313 doi 10 3159 torrey d 14 00091 1 S2CID 85807727 a b Elias Scott A Van Devender Thomas R 1990 09 01 Fossil insect evidence for late Quaternary climatic change in the Big Bend region Chihuahuan Desert Texas Quaternary Research 34 2 249 261 Bibcode 1990QuRes 34 249E doi 10 1016 0033 5894 90 90035 J S2CID 140539014 a b Quercus hinckleyi Texas Parks amp Wildlife Nixon K et al 1998 Quercus hinckleyi IUCN Red List of Threatened Species doi 10 2305 iucn uk 1998 rlts t30955a9595490 en a b Backs Janet Rizner Terry Martin Ashley Mary V 2016 01 05 Using Genetic Analysis to Evaluate Hybridization as a Conservation Concern for the Threatened Species Quercus hinckleyi C H Muller Fagaceae International Journal of Plant Sciences 177 2 122 131 doi 10 1086 684177 ISSN 1058 5893 S2CID 88294300 External links editUSDA Plants Profile for Quercus hinckleyi Tropicos org Photo of herbarium specimen collected in Texas in 1950 Retrieved from https en wikipedia org w index php title Quercus hinckleyi amp oldid 1170162323, wikipedia, wiki, book, books, library,
