[PCA] Delisting of Agave arizonica (Arizona agave) From the Federal List of Endangered and Threatened Wildlife and Plants
Patricia_DeAngelis at fws.gov
Patricia_DeAngelis at fws.gov
Thu Jun 22 14:15:42 CDT 2006
For full notice, see: http://epa.gov/EPA-SPECIES/2006/June/Day-19/
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[Federal Register: June 19, 2006 (Volume 71, Number 117)]
[Rules and Regulations]
[Page 35195-35198]
>From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr19jn06-19]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
RIN 1018-AI79
Endangered and Threatened Wildlife and Plants; Delisting of Agave
arizonica (Arizona agave) From the Federal List of Endangered and
Threatened Wildlife and Plants
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Final rule.
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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), under the
Endangered Species Act of 1973, as amended (Act), have determined that
it is appropriate to remove Agave arizonica (Arizona agave) from the
Federal List of Endangered and Threatened Wildlife and Plants. This
determination is based on a thorough review of all available data,
which indicate that this plant is not a discrete taxonomic entity and
does not meet the definition of a species under the Act. Evidence
collected subsequent to the listing indicates that plants attributed to
Agave arizonica do not constitute a distinct species but rather are
individuals that have resulted from recent and sporadic instances of
hybridization between two species. Current taxonomic practice is not to
recognize such groups of individuals as a species. Since Agave
arizonica is not recognized as a species, it no longer qualifies for
protection under the Act.
DATES: This rule is effective July 19, 2006.
ADDRESSES: Supporting documentation for this rulemaking is available
for public inspection, by appointment, during normal business hours at
the Arizona Ecological Services Field Office of the U.S. Fish and
Wildlife Service, 2321 West Royal Palm Road, Suite 103, Phoenix,
Arizona 85021-4951.
FOR FURTHER INFORMATION CONTACT: Mima Falk, U.S. Fish and Wildlife
Service, located in the Arizona Ecological Services Tucson Sub-office,
201 North Bonita Avenue, Suite 141, Tucson, Arizona 85745 (telephone
520/670-6150 ext. 225; facsimile 520/670-6154).
SUPPLEMENTARY INFORMATION:
Background
Agave arizonica, a member of the agave family, was first discovered
by J.H. Houzenga, M.J. Hazelett, and J.H. Weber in the New River
Mountains of Arizona. Drs. H.S. Gentry and J.H. Weber described this
species in the ``Cactus and Succulent Journal'' in 1970 (Gentry and
Weber 1970). This perennial succulent has leaves growing from the base
in a small basal rosette (i.e., an arrangement of leaves radiating from
a crown or center), and is approximately 20-35 centimeters (cm) (8-14
inches (in)) high and 30-40 cm (12-16 in) wide. The leaves are dark
green with a reddish-brown to light gray border extending nearly to the
base, approximately 13-31 cm (5-12 in) long and 2-3 cm (1 in) wide. The
slender, branched flowering stalk is 2.5-4 meters (m) (8.2-13 feet
(ft)) tall with urn-shaped flowers 25-32 millimeters (mm) (1 in) long
(Hodgson 1999). Some plants, including Agave arizonica, are able to
produce copies of themselves without sexual reproduction. These copies
(clones) may remain physically connected to the original plant
(vegetative offsets) or may be physically separate plants.
Agave arizonica is found on open slopes in chaparral or juniper
grassland in Gila, Maricopa, and Yavapai counties between 1,100-1,750 m
(3,600-5,800 ft) in elevation. The plants are often found associated
with native junipers (Juniperus spp.), mountain mahogany (Cercocarpus
montanus), Opuntia spp., sotol (Nolina microcarpa), and banana yucca
(Yucca baccata), among other species common to the chaparral/juniper-
oak transition (Hodgson and DeLamater 1988). There are estimated to be
fewer than 100 plants in the wild, occurring mainly on the Tonto
National Forest and a few locations on private property. Agave
arizonica plants are associated with shallow, cobbled, and gravelly
soils on strongly sloping to very steep slopes and rock outcrops on
mid-elevation hills and mountains. The soils are well-drained and
derived from a variety of rocks, including granite, gneiss, rhyolite,
andesite, ruffs, limestone, sandstone, and basalt (Hodgson and
DeLamater 1988). Plants typically flower from May to July.
Field studies on Agave arizonica began in 1983. A natural
distribution study was not finalized until August 1984 (DeLamater
1984), after the final listing rule (49 FR 21055, May 18, 1984) was
published. Surveys for this study were conducted in the New River
Mountains, and by 1984, ten new clones were found in these mountains.
These were individual clones of 2-5 rosettes. All of the clones
occurred together with two other agaves, Agave toumeyana ssp. bella and
A. chrysantha, neither of which is considered rare. A. chrysantha is
found in southern and eastern Yavapai County, through much of Gila and
Maricopa counties, northern and eastern Pinal County, and northeastern
Pima County. Agave toumeyana ssp. bella is restricted to the eastern
slope of the Bradshaw Mountains in eastern Yavapai to northwestern and
central to southern Gila County, and northeastern Maricopa to northern
Pinal County.
A comparison of plant characters showed Agave arizonica to be
intermediate to the other two agave species with which it is always
found in association (DeLamater and Hodgson 1986). Pinkava and Baker
(1985) suggested that plants recognized as Agave arizonica may be the
result of continuing production of hybrid individuals rather than a
distinct species, based on observations that hybrid individuals are
found only where the ranges of the putative parents overlap; they are
found only in random, widely scattered locations of individual plants
and clones; their putative parents have overlapping flowering periods;
Agave arizonica's morphological characters are intermediate between the
putative parents; and, they appeared to be subfertile (reduced
fertilization), producing pollen with a low percent of stainability (a
measure of pollen viability). Agave arizonica has the same chromosome
count ((2n) of 60) as both of its parents which allows for continued
reproduction with its parents (backcrossing). Polyploidy (a genetic
variation wherein an individual plant has more than the two normal sets
of homologous chromosomes) is one factor in determining if a hybrid
between two species can become genetically stable. This condition is
not present in the genetic constitution of Agave arizonica.
Survey work continued in areas that supported populations of the
two parent species. These surveys resulted in the discovery of two
clones in the Sierra Ancha Mountains, 100 miles disjunct from the New
River Mountain locations. To date, plants and clones have been
identified in three areas on the Tonto National Forest (New River
Mountains, Sierra Ancha Mountains, and the Humboldt Mountains). The New
River population is the most numerous, located 17.94 kilometers (km)
(10.7 miles (mi)) west-northwest of the Sierra Ancha population. Only
one individual was found in the Serra Anch Mountains (Tr[auml]bold
2001). The Humboldt Mountains support a population of Arizona agave, as
well as another agave hybrid. This different hybrid agave is produced
from a cross between A. toumeyana ssp. toumeyana and A. chrysantha
(Pinkava and Baker 1985). That hybrid is a triploid (3n=90), and
therefore has a different chromosome count than Agave arizonica.
[[Page 35196]]
The Desert Botanical Garden (DBG), in Phoenix, initiated ecological
studies of Agave arizonica in the mid-1980s through 1994. They
conducted numerous surveys on the Tonto National Forest, collected
seeds in situ (in the natural or original environment), conducted
experimental crosses in situ and ex situ (in an artificial
environment), and started an ex situ collection. DBG's work has shown
that Agave arizonica can produce viable seed. In 1985, three different
crosses were performed on clone #52, in situ, using flowers
from different panicles (flower stalks). One cross used frozen pollen
collected from Agave arizonica at the DBG, the second cross was self-
fertilization of clone #52, and the third cross was
uncontrolled outcrossing of clone #52 (flowers were left open
to be pollinated by various donors). Seed was collected from all three
crosses. Cross #1 produced 250 seeds, cross #2 produced
20 seeds, and cross #3 produced a large quantity of seeds
(Hodgson and DeLamater 1988). Outcrossing with Agave arizonica pollen
(Cross #1) produced a high proportion of viable seed, as did
uncontrolled outcrossing (Cross #3), while self-fertilization
(Cross #2) produced a poor seed set. The majority of the seeds
were planted. Ten months after planting, 10 of the 105 seeds produced
from cross #1 germinated. Some of those resembled Agave
arizonica, while others did not (W. Hodgson, Desert Botanical Garden,
pers. comm. 2003). DBG also conducted controlled crosses of A.
chrysantha and A. toumeyana ssp. bella. The seeds produced from this
cross resulted in Agave arizonica plants. Individual Agave arizonica
plants can therefore be created by crosses of the parental species.
These results support the hypothesis that Agave arizonica is composed
of individuals that resulted from recent and spontaneous instances of
hybridization between two species, and is not, at this time, a species
of hybrid origin.
Agave arizonica is most likely a first-generation (F1) hybrid
between two other species. It is not known if any individuals of the F1
generation, in situ, have backcrossed with either one of the parents or
with another Agave arizonica individual. The latter seems unlikely
given the low numbers of individuals and the great distance separating
them. Seeds have been produced in the wild, but it is not known if
those seeds were produced from crosses of Agave arizonica and either
parent species or Agave arizonica and Agave arizonica. Seeds grown out
in greenhouse conditions produced plants with wide phenotypic (visible)
variations; not all seedlings presented `pure' Agave arizonica traits.
The fact that Agave arizonica can be reliably produced by crossing the
putative parents ex situ lends support to the hypothesis that Agave
arizonica is a recurring F1 hybrid. All evidence supports that Agave
arizonica individuals are derived from crosses between different
species. In other words, each individual Agave arizonica was created
spontaneously and independently from separate crossings of the putative
parental species (M. Baker, pers. comm. 2004).
Agave arizonica plants are rare in the wild. The likelihood is low
that two of these plants would breed with one another because it is
unlikely that two such plants would be close enough to one another and
bloom in the same year. Clones still attached or near to the parent
plant may produce flowers at the same time, but spatially separated
clones may not all bloom at the same time. The flowering period of
Agave arizonica overlaps with that of its putative parents, and the
same insects (bumblebees, mining bees of the family Halictidae, and
solitary bees) visit all three agave species. This condition can lead
to back-crosses with one of the putative parents. Agave arizonica is
not likely to maintain a separate genetic identity due to low numbers,
overlap of flowering period with the putative parents, and lack of an
effective reproductive isolating mechanism to promote genetic
stability.
In 1999, Hodgson published a treatment for the Agave family for the
``Flora of Arizona'' (Hodgson 1999). Agave arizonica was not recognized
as a species in that treatment, which indicated that it should be
referred to as Agave arizonica, a hybrid of recent origin involving A.
chrysantha and A. toumeyana var. bella.
Jolly (in Riesberg 1991) has suggested protection for a hybrid
taxon if (1) its evolution has gone past the point where it can be
reproduced through crossing of its putative parents, (2) it is
taxonomically distinct from its parents, and (3) it is sufficiently
rare or imperiled. Under these criteria, F1 hybrids such as Agave
arizonica should receive no protection because it is still backcrossing
with its parents and is not taxonomically distinct.
In summary, the plant species formerly referred to as Agave
arizonica is now recognized as an interspecific hybrid produced
sporadically and spontaneously by the cross of Agave chrysantha and
Agave toumeyana var. bella. Individuals have been determined to be
hybrids for the following reasons: (1) They share the same chromosome
number (2n=60) with the putative parents, indicating that there are no
chromosomal barriers (i.e., reproductive isolating mechanisms) in place
to facilitate genetic stability, (2) flowering periods of the putative
parents overlap, (3) morphological characters of Agave arizonica are
intermediate with those of the putative parents, (4) Agave arizonica
only occurs where there is overlap with the putative parents, (5) it
appears to be subfertile, producing pollen with low percent
stainability, (6) Agave arizonica can be created, ex situ, by crossing
the putative parents, indicating that there may be no unique genetic
characters associated with these plants, and (7) it has not, to our
knowledge, reproduced sexually in the field.
Previous Federal Action
Federal Government action concerning Agave arizonica began with
section 12 of the Act, which directed the Secretary of the Smithsonian
Institution to prepare a report on those plants considered to be
endangered, threatened, or extinct. This report (House Document No. 94-
51), which included Agave arizonica, was presented to Congress on
January 9, 1975, and accepted by the Service under section 4(c)(2), now
section 4(b)(3)(A), of the Act as a petition to list these species. The
report, along with a statement of our intention to review the status of
the plant taxa, was published in the Federal Register on July 1, 1975
(40 FR 27823). On June 16, 1976, we published a proposed rule in the
Federal Register (41 FR 24523) to determine approximately 1,700
vascular plants to be endangered pursuant to section 4 of the Act.
Agave arizonica was included in this proposal. On December 10, 1979, we
withdrew all outstanding proposals not finalized within two years of
their first publication, as required by the 1978 amendments to the Act.
On August 26, 1980, the Service received a status report prepared by
four researchers employed by the Museum of Northern Arizona. This
report documented the status of, and threats to, the species. On
December 5, 1980, we published a revised notice for plants (45 FR
82479) and included Agave arizonica in category 1. Category 1 was
comprised of taxa for which we had sufficient biological information to
support their being listed as endangered or threatened species. We
published a proposed rule to list Agave arizonica as an endangered
species on May 20, 1983 (48 FR 22757). No critical habitat was
proposed. The final rule listing Agave arizonica as endangered was
published on May 18,
[[Page 35197]]
1984 (49 FR 21055), and no critical habitat was designated.
In 1985, a year after Agave arizonica was listed, the U.S.
Department of Agriculture Forest Service petitioned us to delist Agave
arizonica because of its hybrid status. We sent out the work on Agave
arizonica that had been published for peer review and solicited
comments. Many of the comments supported delisting based on the
available evidence; however, the Service disagreed that the available
data conclusively proved that Agave arizonica was a hybrid. The Service
believed that the results of the controlled crosses were important for
the analysis, and those had not been completed at the time of the
review. Therefore, on January 21, 1987 (52 FR 2239), we announced that
delisting was not warranted.
We published a proposed rule to remove Agave arizonica from the
Federal List of Endangered and Threatened Plants on January 11, 2005
(70 FR 1858), based on additional information indicating that Agave
arizonica is a hybrid and does not meet the definition of a species as
defined by the Act.
Summary of Comments and Recommendations
In the January 11, 2005, proposed rule (70 FR 1858) and associated
notifications, we invited all interested parties to submit comments or
information that might contribute to the final delisting determination
for this species. The public comment period ended March 14, 2005. We
contacted and sent announcements of the proposed rule to appropriate
Federal and State agencies, county governments, scientific
organizations, and other interested parties. In addition, we solicited
formal scientific peer review of the proposal in accordance with our
July 1, 1994, Interagency Cooperative Policy for Peer Review in
Endangered Species Act Activities (59 FR 34270). We requested five
individuals with expertise in one or several fields, including
familiarity with the species, familiarity with the geographic region in
which the species occurs, and familiarity with the principles of
taxonomy, to review the proposed rule by the close of the comment
period. We received comments from six parties, including three
designated peer reviewers. All three of the responding peer reviewers,
the U.S. Department of Agriculture Forest Service, and one public
commenter agreed with our assessment that the scientific evidence
presented in our proposed rule supports the hybrid status of Agave
arizonica and, therefore, the plant does not merit protection under the
Act. The comments are addressed in the following summary. We did not
receive any requests for a public hearing.
Issue: We are too hasty in our proposal to delist Agave arizonica
because hybrids can often succeed in combining genes in new ways to
become successful breeding populations, leading to new species
formation.
Our Response: Many vascular plants are of hybrid origin, and we
acknowledge that hybrids play an important role in speciation. Current
evidence does not support the view that Agave arizonica is a successful
breeding population. We based our delisting decision upon the best
available scientific and commercial information. After a review of all
available data, we have made the determination that Agave arizonica
does not meet the definition of a species under the Act. If new
information becomes available that shows Agave arizonica is exhibiting
characteristics of a species (i.e., reproductive isolation from the
parent species and ability to reproduce sexually and maintain a degree
of genetic stability), we will reexamine the threats to determine if it
should be listed again.
Delisting Analysis
After a review of all information available, we are removing Agave
arizonica from the List of Endangered and Threatened Plants, 50 CFR
17.12. Section 4(a)(1) of the Act and regulations (50 CFR part 424)
issued to implement the listing provisions of the Act set forth the
procedures for adding species to or removing them from Federal lists.
The regulations at 50 CFR 424.11(d) state that a species may be
delisted if (1) it becomes extinct, (2) it recovers, or (3) the
original classification data were in error. Since the time of listing,
additional study has shown that Agave arizonica is not a distinct
species, but consists of individuals that are the result of
spontaneous, occasional, and continuing hybridization between two other
distinct species. Individual hybrid plants are produced within
populations of the parental species, but their production is random. In
modern taxonomic practice, such groups of individuals are not
recognized as species. We have concluded that the original taxonomic
interpretation upon which the listing decision was based has not been
substantiated by subsequent studies, and Agave arizonica does not
qualify for protection because it does not fit the definition of a
species under the Act.
The term ``species,'' as defined in the Act, includes any
subspecies of fish or wildlife or plants, and any distinct population
segment of any species or vertebrate fish or wildlife which interbreeds
when mature. Agave arizonica does not meet this definition because it
is not known to interbreed in situ or otherwise reproduce itself.
Hybrid origin of species is considered common within the flowering
plants (Grant 1963), and some species of hybrid origin are capable of
reproducing themselves and maintaining a degree of genetic stability.
However, scientific evidence at this point supports the determination
that Agave arizonica does not have these characteristics of a species.
The plants are not known to have sexually reproduced in situ. Agave
arizonica plants have sporadically developed in situ from the putative
parents, but have not been reproductively self-sustaining. Agave
arizonica has never been found in well-developed populations or outside
patches of its putative parents.
We have carefully assessed the best scientific and commercial
information available regarding the conclusion that Agave arizonica is
not a species, and therefore does not qualify for protection under the
Act. We, therefore, conclude that Agave arizonica no longer warrants
listing under the Act.
Effects of the Rule
This action removes Agave arizonica from the List of Endangered and
Threatened Plants. The prohibitions and conservation measures provided
by the Act no longer apply to this species. Therefore, interstate
commerce, import, and export of Agave arizonica are no longer
prohibited under the Act. In addition, Federal agencies no longer are
required to consult with us to insure that any action they authorize,
fund, or carry out is not likely to jeopardize the continued existence
of Agave arizonica. The plant is still protected by Arizona's Native
Plant Law, A.R.S., Chapter 7, Section 3-901, which specifically
prohibits collection except for scientific or educational purposes
under permit. There is no designated critical habitat for this species.
Future Conservation Measures
The 1988 amendments to the Act require that all species delisted
due to recovery be monitored for at least five years following
delisting. Agave arizonica is being removed from the List of Endangered
and Threatened Plants because the taxonomic interpretation that it is a
species is no longer believed
[[Page 35198]]
to be correct; Agave arizonica is a sporadically occurring hybrid,
rather than a distinct taxon. Therefore, no monitoring period following
delisting is required.
National Environmental Policy Act
We have determined that an Environmental Assessment or an
Environmental Impact Statement, as defined under the authority of the
National Environmental Policy Act of 1969, need not be prepared in
connection with regulations adopted pursuant to section 4(a) of the
Act. We published a notice outlining our reasons for this determination
in the Federal Register on October 25, 1983 (48 FR 49244).
Paperwork Reduction Act
Office of Management and Budget (OMB) regulations at 5 CFR part
1320 implement provisions of the Paperwork Reduction Act (44 U.S.C.
3501 et seq.). The OMB regulations at 5 CFR 1320.3(c) define a
collection of information as the obtaining of information by or for an
agency by means of identical questions posed to, or identical
reporting, recordkeeping, or disclosure requirements imposed on, 10 or
more persons. Furthermore, 5 CFR 1320.3(c)(4) specifies that ``ten or
more persons'' refers to the persons to whom a collection of
information is addressed by the agency within any 12-month period. For
purposes of this definition, employees of the Federal Government are
not included. The Service may not conduct or sponsor, and you are not
required to respond to, a collection of information unless it displays
a currently valid OMB control number.
This rule does not include any collections of information that
require approval by OMB under the Paperwork Reduction Act. The Agave
arizonica is being delisted because the taxonomic interpretation that
it is a species is no longer believed to be correct; Agave arizonica is
a sporadically occurring hybrid, rather than a distinct taxon.
Therefore, no monitoring period following delisting would be required,
and we do not anticipate a need to request data or other information
from 10 or more persons during any 12-month period in order to satisfy
monitoring information needs. If it becomes necessary to collect
information from 10 or more non-Federal individuals, groups, or
organizations per year, we will first obtain information collection
approval from OMB.
Executive Order 13211
On May 18, 2001, the President issued Executive Order 13211 on
regulations that significantly affect energy supply, distribution, and
use. Executive Order 13211 requires agencies to prepare Statements of
Energy Effects when undertaking certain actions. As this final rule is
not expected to significantly affect energy supplies, distribution, or
use, this action is not a significant energy action and no Statement of
Energy Effects is required.
References Cited
DeLamater, R. 1984. Natural distribution and status of Agave
arizonica Gentry and Weber in Arizona with accompanying maps.
Prepared for USDA Forest Service Range Management, Albuquerque, NM.
11 pp.
DeLamater, R. and W. Hodgson. 1986. Agave arizonica: An endangered
species, a hybrid, or does it matter? Proceedings of a California
Native Plant Society Conference. Sacramento, CA.
Gentry, H.S. and J.H. Weber. 1970. Two New Agaves in Arizona. Cactus
and Succulent Journal. 42(5): 223-228.
Grant, V. 1963. The Origin of Adaptations. Columbia University
Press, New York. 606 pp.
Hodgson, W. and R. DeLamater. 1988. Agave arizonica Gentry and
Weber; Summary of status and report on recent studies. Desert
Botanical Gardens, Phoenix, AZ. U.S.D.I., U.S. Fish and Wildlife
Service, Albuquerque, NM. 11 pp.
Hodgson, W. 1999. Vascular plants of Arizona: Agavaceae. Journal of
Arizona-Nevada Academy of Science 32(1): 1-21.
Pinkava, D.J. and M.A. Baker. 1985. Chromosome and hybridization
studies of agaves. Desert Plants. 7(2): 93-100.
Riesberg, L.H. 1991. Hybridization in rare plants: insights from
case studies in Cercocarpus and Helianthus. In Genetics and
conservation of rare plants. Donald A. Falk and K.E. Holsinger
(Eds). Oxford University Press, New York. 283 pp.
Tr[auml]bold, P.A. 2001. Re-establishment--Agave arizonica. M.S.
thesis. California State University, Fullerton, CA. 65 pp.
Authors
The primary authors of this document are staff located at the
Arizona Ecological Services Tucson Sub-office (see FOR FURTHER
INFORMATION CONTACT section).
List of Subjects in 50 CFR Part 17
Endangered and threatened species, Exports, Imports, Reporting and
recordkeeping requirements, Transportation.
Regulation Promulgation
? Accordingly, we hereby amend part 17, subchapter B of chapter I, title
50 of the Code of Federal Regulations, as set forth below:
PART 17--[AMENDED]
? 1. The authority citation for part 17 continues to read as follows:
Authority: 16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C.
4201-4245; Public Law 99-625, 100 Stat. 3500; unless otherwise
noted.
Sec. 17.12 [Amended]
? 2. Amend Sec. 17.12(h) by removing the entry ``Agave arizonica'' under
``FLOWERING PLANTS'' from the List of Endangered and Threatened Plants.
Dated: May 19, 2006.
Kenneth Stansell,
Acting Director, Fish and Wildlife Service.
[FR Doc. E6-8643 Filed 6-16-06; 8:45 am]
BILLING CODE 4310-55-P
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