Lab 1 (GROUP G) Exercise Reading Questions
Table 1.1 Systolic blood pressure of women taking and not taking oral contraceptives (birth control)
Pop. 1 (oral contraceptive users)
Pop. 2 (non-oral contraceptive users)
Pop. 3a (before oral contraceptive)
Pop. 3b (during oral contraceptive)
140
140
115
128
144
130
112
115
132
120
107
106
125
128
119
128
137
126
115
122
133
131
138
145
139
127
126
132
123
110
105
109
130
122
104
102
138
117
115
117
Q1
What is the mean of population 1?
Q2
What is the mean of population 2?
Q3
What is the mean of population 3?
Q4
What is the mean population of 3b?
Q5
What is the variance of population 1?
Q6
What is the variance of population 2?
Q7
What is the variance of population 3?
Q8
What is the variance of population 3b?
Q9
What is the t statisctic for the t test (two sample assuming) equal variance comparing population 1 and 2?
Q10
What is the t statistic for the paired t test comparing population 3a and 3b?
Q11
What is the one tail p value for t test (two sample assuming) comparing populations 1 and 2?
Q12
What is the one tail p value for paired t test comparing population 3a and 3b?
Q13
The P value for both t test was less than 0.05, in the null hypothesis rejected?
o YES
o NO
Q14
Which of the following is the null hypothesis is for the t test comparing population 1 and 2?
o There is a diffrence in mean systolic pressure in two population.
o There is no diffrence in mean systolic pressure in two populations.
Environmental effects on bacterial community structure in a hypersaline estuarine ecosystem
E.L. Schuenzel1, M. Guzman1,2, E. Reyes1, H. Deyoe1, K. Lowe1
1Department of Biology, University of Texas Rio Grande Valley, 1201 W University Drive, Edinburg, TX 78539
2University of Texas San Antonio
Co
esponding Author:
Erin Schuenzel
Department of Biology
University of Texas Rio Grande Valley
1201 W University Drive
Edinburg, TX 78539
Phone: XXXXXXXXXX
Email: XXXXXXXXXX
Introduction
Up until the 1960’s, it was thought that life could only be sustained in a na
ow set of conditions, such as a neutral pH and an atmospheric pressures of about 1 atm (Bonch-Osmolovskaya and Atomi, XXXXXXXXXXWe now know this to be inco
ect and are well aware of countless ecosystems worldwide that flourish in environments outside of what is considered normal. Halophiles, for example, are organisms that possess attributes which allow them to grow and reproduce in high salinity concentrations (Bonch-Osmolovskaya and Atomi, XXXXXXXXXXThe Laguna Madre of Texas (USA) is just one environment where halophiles are uniquely suited to not only survive, but to thrive.
The Laguna Madre (“Mother Lagoon”) of Texas, along with the Laguna Madre de Tamaulipas Mexico, form one of two hypersaline, estuarine ecosystems in North America and one of only five hypersaline estuaries in the world. The Laguna Madre is categorized as a shallow estuary with an average depth of 1.4 m, a length of 185 km, and a width ranging from 6 to 12 km (Tunnel and Judd, XXXXXXXXXXThis distinct location is divided into two subunits, the Upper Laguna Madre and the Lower Laguna Madre, which are separated by a land-
idge known as the Land Cut or Saltillo Flats that formed over thousands of years as a result of deposition and sedimentation (Bynes and Berlinghoff, XXXXXXXXXXThe Lower Laguna Madre, the focus of this study, is bordered to the north by the Land Cut, to the east by Padre Island, and to the west by the Texas mainland.
The climate of south Texas and the Lower Laguna Madre has been classified as semiarid (Thornthwaite, 1948; Hedgepeth, 1953), as a subtropical steppe (Norwine et al., 1977), and as a subhumid-to-semiarid east-coast subtropical climate (Ful
ight et al., XXXXXXXXXXThe regional climate includes an average annual precipitation of 70 cm (mainly rainfall). However, precipitation amounts can be negatively affected by periodic droughts or positively affected by tropical storms and hu
icanes. The average annual temperature in 23°C but long, hot summers yield temperatures greater than 30°C for several weeks. The semiarid nature of the region combined with high temperatures and wind tides results in very high evaporation of the Lower Laguna Madre’s water. Evaporation rates may exceed precipitation by 2-3 times in some years thus lowering the water depth and concentrating salts in the water (Onuf, 2007).
The Lower Laguna Madre is considered a hypersaline ecosystem because the average salinity is typically 30 ppt or slightly higher (Whelan et al., 2005), but rarely exceeding 50 ppt (Onuf, XXXXXXXXXXSeveral factors contribute to the hypersaline nature of the estuary in addition to high evaporation rates, such as limited water circulation within the lagoon, limited water exchange with the Gulf of Mexico, and little or inconsistent freshwater influx into the estuary. Freshwater input into the Lower Laguna Madre is primarily via the A
oyo Colorado, a man-made channel of the Rio Grande delta system, which drains ranching, citrus and other agricultural lands in south Texas (Tunnel and Judd, 2002; Onuf, 2007).
Although the macro-ecology of the Lower Laguna Madre has been studied intensively for decades, little is known about the microbial ecology of the ecosystem. Bacteria are known to be important to the function and balance of marine ecosystems because of their contribution to nutrient cycling, including ca
on cycling (Jochem et al., XXXXXXXXXXChin-Leo and Benner XXXXXXXXXXfound that while seagrasses support the secondary productivity of the LLM, bacteria are essential for the transfer of ca
on from the seagrass detritus to higher trophic levels because seagrasses cannot be directly utilized by animals. Also, microorganisms that reside within extreme environments often possess unique metabolic processes and enzymes that may have biotechnological applications (Hollister et al., XXXXXXXXXXSeveral previous studies by our laboratory examined specific microbial populations using principally culture-dependent techniques complemented by limited DNA sequencing or other molecular processes (Berlanga et al., 2009; Molina et al., 2001; Espinosa et al., 2008; Elizondo et al., XXXXXXXXXXCulture-dependent methods, however, fail to define the immense bacterial communities present in ecosystems because 99% of the bacterial diversity is un-culturable (Vaz-Moreira et al., 2011).
To gain a
oader perspective of the resident microbial population and communities within the Lower Laguna Madre, the next-generation DNA sequencing protocol sequencing by synthesis was employed to identify operational taxonomic units (OTUs) in a less biased sampling of the bacterial communities. Several studies using next-generation sequencing techniques have focused on elucidating the microbial communities of many different ecosystems. The characterization of microbial communities in hypersaline environments, however, are few in number and most either focus on aquatic communities or microbial mats (Oren, 2002; Humayoun et al., 2003; Mutlus et al., 2008; Moune et al., 2003; Ley et al., XXXXXXXXXXThose that do focus on hypersaline sediment focus on only the characterization of the communities (Kim et al., 2012) or attempt to co
elate the community structure to different abiotic conditions, such as salinity, pH, or phosphorus levels (Swan et al., 2010, Hollister et al., XXXXXXXXXXAlmost none focus on the differences within bacteria communities in relation to time and none focus on communities found within hypersaline estuary sediments.
In this study, we performed sequencing by sequencing and 16S rRNA OTU analysis on samples taken from multiple locations in the Lower Laguna Madre over three consecutive years in order to examine the plasticity of the microbial communities inhabiting sediments. Microbial communities were compared spatially across eight locations and temporally across three years with sampling occu
ing within the same month each year. The possible effects of the abiotic factors of salinity, pH, and dissolved oxygen on bacterial community structure were also analyzed for co
elations.